The One Button Mystique

I enjoy my iPhone, but I can't quite come to terms with one aspect of its design: Apple's insistence that there can be only ever be one, and only one, button on the front of the device.

I also own a completely buttonless Kindle Fire, and you'll get no argument from me that there should be at least one obvious "Jesus Handle" button on the front of any gadget. I do wonder why Amazon decided to make the Fire buttonless, when every other Kindle they ship has a home button. Amazon has a track record of making some awfully rough version 1.0 devices; I'm sure they'll add a home button in a version or two. And, hey, at only $199 I'm willing to cut them a little slack. For now.

Even Apple is no stranger to buttonless devices. Consider the oddly buttonless third generation iPod Shuffle, where you had to double and even triple click the controls on the headphones to do basic things like advance tracks. Oh, and by the way, this also made every set of headphones you own obsolete, at least for use with this model. The fourth gen shuffle rapidly switched back to physical controls on the device, and the fifth gen went to touch controls on the device, as expected.

Microsoft is just as guilty. I sometimes struggle with the otherwise awesome Xbox 360 Wireless Microphone. It has only a power button and some lights.

In its defense, for the most part it does just work when you pick it up and start singing (badly, in my case), but I admit to being slightly perplexed every time I have to sync it with an Xbox, or figure out what's going on with it. Can you blame me?

When you turn on the microphone, the built-in lights shine to display the microphone status as follows:

• Power on: lights flash green one time every second
• Connecting: lights flash green four times every second
• Connection complete: lights flash blue, and then stops

When your battery power is low, the built-in lights shine to display the battery charge status as follows:

• Low: Lights flash amber one time every three seconds
• Critical: Lights flash amber one time every second

When your microphone moves out of the wireless range of your console, the lights flash green one time every second. The lights can also change color together with supported game titles.

If we can agree that no buttons is clearly a bad idea, I think it follows that one button is problematic in its own way. I have the same issue with the single button on the iPhone that I do with the single button mouse – it may be OK-ish at the very beginning, but over time it leads to absurd, almost comical overloading of functionality. Consider how many different things the single button on the face of an iPhone now controls:

(diagram courtesy Andrew Durdin, source)

The iPhone home button? Why, it's easy! You have your choice of…

• single-click
• double-click
• triple-click
• click and hold
• click and pause and click again

All of which have different meanings at different times, of course. In particular I spend a lot of time double-clicking to get to the active apps list, and I often mis-tap which kicks me over to the home screen. I have so many apps installed on my iPhone that search is the only rational way to navigate. This means I search a lot, which requires clicking once to get to the default home page, pausing, then clicking again. Sometimes I click too long, which is then detected as click-and-hold, and I get the voice search app which I am … er, not a fan of, to put it mildly.

I've gotten to the point where I dread using the home button on my iPhone because it Makes Me Think. And I get it wrong a significant percentage of the time. This isn't the way it's supposed to be.

You might be expecting me to turn into a rabid Windows Phone or Android fanboy about now and snarkily note how they get it right. I'm not sure they do. Either of them. They all manage to suck in their own special way.

When there's one button on the device, at least it's clear what that button is supposed to do, right? Well, sometimes.

There is one theme I agree with here – the clearly marked back button on both Android and Windows phones, just like a web browser. I mostly use my iPhone as a platform for the Internet, and the simplicity of the Internet is its primary strength: a collection of obvious things to click, and an easy, giant honking back button so you never get lost in its maze of twisty passages, all alike. It is true that browsers have a home button, but the latest versions of Chrome, Firefox, and Internet Explorer have all but pushed that home button off the UI in favor of the ginormous back button. While I'll tentatively agree that not all phone apps have to behave like the Internet, the Internet is becoming more and more of a platform for bona fide applications every day. The back button is a UI paradigm that works like gangbusters for webapps, and I'd argue strongly in favor of that being a hard button on a device.

But once you add three buttons, thinking starts to creep in again. Am I pressing the correct button? That's never good. And I don't even know what that third button is supposed to be on the Android phone! I could possibly be in favor of the hard search button on the Windows phone, I suppose, but I'd rather see good, consistent use of two buttons on the face of a device before willy-nilly adding Yet Another Button. I think there's a reason the industry has more or less standardized on a two-button mouse, for example. (Yes, there is that pesky middle button, but it's a nice to have, not an essential part of the experience.)

What about the one finger solution? Even with touch devices, one finger does not seem to be enough; there's a curious overloading of the experience over time.

On the iPad, there are a number of system-wide gestures, such as swiping left or right with four fingers to switch between apps. Four-finger swipes? That's convoluted, but imagine a virtual mixing console with horizontal sliders. Quickly move four of them at once...and you switch apps. Application designers have to work around these, making sure that legitimate input methods don't mimic the system-level gestures.

The worst offender is this: swipe down from the top of the screen to reveal the Notification Center (a window containing calendar appointments, the weather, etc.). A single-finger vertical motion is hardly unusual, and many apps expect such input. The games Flight Control and Fruit Ninja are two prime examples. Unintentionally pulling down the Notification Center during normal gameplay is common. A centered vertical swipe is natural in any paint program, too. Do app designers need build around allowing such controls? Apparently, yes.

Yes, our old friend overloading is now on the touch scene in spades: for all but the simplest use of a tablet, you will inevitably find yourself double-tapping, tapping and holding, swiping with two fingers, and so on.

Apple's done a great job of embodying simplicity and clean design, but I often think they go too far, particularly at the beginning. For example, the first Mac didn't even have cursor keys. Everything's a design call, and somewhat subjective, but like Goldilocks, I'm going to maintain that the secret sauce here is not to get the porridge too cold (no buttons) or too hot (3 or more buttons), but just right. I'd certainly be a happier iPhone user if I didn't have to think so much about what's going to happen when I press my home button for the hundredth time in a day.

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

Defeating SOPA and PIPA Isn't Enough

SOPA and PIPA are two pieces of proposed legislation designed to "stop" Internet piracy… in the most hamfisted way imaginable. As Mitchell Baker explains:

Assume there's a corner store in your neighborhood that rents movies. But the movie industry believes that some or even all of the videos in that store are unauthorized copies, so that they're not being paid when people watch their movies. What should be done?

SOPA/PIPA do not aim at the people trying to get to the store, or even the store itself. The solution under the proposed bills is to make it as difficult as possible to find or interact with the store:

1. Maps showing the location of the store must be changed to hide it.
2. The road to the store must be blocked off so that it is difficult to physically get to there.
3. Directory services must delist the store’s phone number and address.
4. Credit card companies would have to cease providing services to the store.
5. Local newspapers would no longer be allowed to place ads for the video store.
6. To make sure it all happens, any person or organization who doesn’t do this is subject to penalties. Even publishing a newsletter that tells people where the store is would be prohibited by this legislation.

Just substitute "corner store" with "website" and I think you can see where this is going. These bills are so rife with potential for abuse and misuse, so clearly dangerous to the very fabric of the Internet, that frankly I have a hard time getting worked up about them. The Internet is under constant siege by large companies, and will be for the forseeable future. This is nothing new. These bills will be defeated, because they must be.

Instead, I'm scratching my head and wondering how such boneheaded bills made it this far in Congress. I can think of a few reasons:

• Average people don't understand how the Internet works and thus can't comprehend the danger.
• Nobody pays attention to what our government does until it hits them in the pocketbook (or below the belt).
• These bills were pushed through by highly paid lobbyists for the entertainment industry.

I often bemoan the state of Slacktivism on the internet, where changing your Facebook or Twitter picture is considered a valid and effective form of protest. But this time, I am happy to say, was indeed different.

Perhaps because of the obvious danger of these bills, geek websites and communities banded together weeks ago to protect themselves and the greater Internet. Like many other technical communities, we wrote about it on our blog, talked about it on our podcast, and even put up a little banner on Stack Overflow for a day. Users were encouraged to call, fax, and write their representatives in Congress and express their concerns. And they did, in droves! But outside of our technical geek ghettos, there was precious little mainstream coverage of this dangerous legislation.

That is, until major sites like Wikipedia, Google, and Craigslist joined the bandwagon today. Most notably, Wikipedia actually went dark for all of today, January 18th, rendering all of English language Wikipedia inaccessible. That turned the tide, and transformed SOPA/PIPA into something that average people would actually talk about and care about. There's no better way to raise awareness of the danger these bills pose than blacklisting one of the greatest resources the Internet has ever produced.

While SOPA/PIPA are still alive -- barely -- for now, I think it's safe to say that they are well on their way to defeat. I'm glad to be a part of that, however tiny, but I cannot in good conscience celebrate.

Yes, we likely succeeded in defeating these two specific bills and galvanizing the political will of major Internet communities, including our very own Stack Exchange. These are good and noble and just and necessary things. They are things to be proud of. But instead of celebrating, let's take this time to reflect and ask ourselves a deeper question: how is it that these dangerous bills came to exist in the first place?

First, and again, this is a critical battle to wage and win. SOPA is just the latest, but in many ways, the most absurd campaign in the endless saga of America’s copyright wars. It will be yet another failed attempt in a failed war, and I obviously believe it should be opposed.

But second, and as you describe, this isn’t my war anymore. Not because my heart isn’t in it, but because I don’t believe we will win that war (or better, win the peace and move on) — even if we can win battles like this one — until the more basic corruption that is our government gets addressed. That’s the fight I have spent the last 4 years working on. That’s where I’ll be for at least the next 6.

For this is what I know: We will never (as in not ever) win the war you care about until we win the war against this corruption of our Republic.

Of course, as my book, Republic, Lost: How Money Corrupts Congress -- and a Plan to Stop It, describes, this is an insanely difficult, possibly impossible, fight. But whether difficult or not, it is the fight that must be waged.

We have done much. But in our celebratory enthusiasm, please take a moment to hear out Mr. Lessig, and appreciate just how far we have yet to go.

So yes, join us in fighting the obvious insanity of legislation like SOPA and PIPA that threaten the open, unfettered Internet. But please, please also join us in attacking the far more pernicious problem of lobbyist money subtly corrupting our government. If we don't deal with that, we will never stop fighting bills like SOPA and PIPA.

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

Building Social Software for the Anti-Social

In November, I delivered the keynote presentation at Øredev 2011. It was the second and probably final presentation in the series I call Building Social Software for the Anti-Social.

I've spent almost four years thinking about the Q&A format, and these two presentations are the culmination of that line of thought. In them I present ten "scary ideas", ideas which are counterintuitive for most folks. These are the building blocks we used to construct Stack Overflow, and by extension, Server Fault, Super User, and the rest of the Stack Exchange network.

1. Radically lower the bar for participation.
2. Trusting (some of) your users.
3. Life is the world’s biggest MMORPG.
4. Bad stuff happens.
5. Love trumps money.
6. Rules can be fun and social.
7. All modern website design is game design.
8. Thoughtful game design creates sustainable communities.
9. The community isn’t always right.
10. Some moderation required.

It's not the same experience as attending the actual live presentation, of course, but you can certainly get the gist of it by viewing the slides for these two presentations online:

The Øredev organizers hired ImageThink to draw each presentation on a whiteboard live on stage as it was presented. I was skeptical that this would work, but the whiteboard visualizations came out great for all the presentations. Here's the two whiteboard drawings ImageThink created during my presentation. (Yes, they had two artists on stage "live whiteboarding", one on the left side, and one on the right side.)

It's not a bad approximation of what was covered. If you're curious about live whiteboard visualizations, ImageThink posted a great set of links on their blog that I highly recommend.

After four years, we've mostly figured out what works and what doesn't work for our particular brand of low noise, high signal Q&A at Stack Exchange. But the title Social Software for the Anti-Social is only partially tongue in cheek. If you want to learn anything online, you have to design your software to refocus and redirect people's natural social group impulses, and that's what these presentations attempt to explain. I hope you enjoy them!

Update: Part II is now available as a full talk, with audio and video courtesy of GitHub. Watch it now!

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

Gifts for Geeks, 2011 Edition

Between founding Stack Overflow (and later, running Stack Exchange) and having a child, I haven't had much time to blog about the holidays for a few years now. The last Gifts for Geeks I did was in 2008. Those recommendations are still as valid as ever, but I just couldn't muster the enthusiasm to do it every year.

I've also come to realize, especially after having a child, that the goal in life is not to own a lot of "stuff", but rather, to free yourself from everything except that which is essential, and that which you love.

I'm still working on this, and I probably will be until I die. That said, there are a few essential things I think any self respecting geek should have, things I use all the time and I truly love – and I feel it's my responsibility to let my fellow geeks, and the spouses and significant others of geeks, know about them. Otherwise you might end up with yet another WiFi Detecting Shirt as a gift this year, and that'd just be … sad, for everyone involved. So consider this a public service, and feel free to share this post, lest you show up to work in January and find yourself and all your coworkers wearing Wifi Detecting Shirts.

As I wrote in What's On Your Utility Belt? I've been carrying LED flashlights since 2005, and just in that time the average LED flashlight has gone from bright, to very bright, to amazingly bright, to ridiculously blinding laser-like bright. You can thank Haitz's Law for that:

[Haitz's Law] states that every decade, the cost per lumen (unit of useful light emitted) falls by a factor of 10, the amount of light generated per LED package increases by a factor of 20, for a given wavelength (color) of light. It is considered the LED counterpart to Moore's law, which states that the number of transistors in a given integrated circuit doubles every 18 to 24 months. Both laws rely on the process optimization of the production of semiconductor devices.

Or, as I like to call it, "why you will be regularly blinded by flashlights for the rest of your natural life." But on the plus side, it also means that today even inexpensive LED flashlights are plenty bright for all but the most niche applications. You no longer have to pay a big premium to get one that's usefully bright. LED lights are so awesome, in fact, that I own and recommend no less than three form factors:

1. Fenix HL21 ($35)

   

   If you do any kind of DIY work at all, at some point you're going to want a focused light exactly where you are looking. If you can get over the "hey, I have this lamp strapped to my head and I look like a dork" factor, headlamps are ridiculously convenient. I had a much less bright (~40 lumens) headlamp and switching to this 90 lumen HL21 was a major improvement. I use this thing all the time. Looking cool is overrated.

2. Fenix E21 ($35)

   

   The E21 is much smaller than your typical full-size flashlight but it is every bit as bright as those giant police-baton like Maglites. It runs off two ubiquitous AA batteries, and has a pleasingly simple design, with an obvious switch in the rear and only two configurable light levels: low (48 lumens) and high (150 lumens). This is a flashlight you could buy your parents without baffling them. We own three, and each of our cars has one in the glove box. This is, in my opinion, what LED lights were meant to be.

3. Fenix LD01R4 ($40)

   

   The latest revision of the LD01 is the proverbial Every Day Carry; a compact single AAA flashlight. As long as you have your keys with you, you'll never without a reliable, bright enough light. Twist the cap to balance between runtime and light output; the three modes are 85 lumens for 1 hour, 28 lumens for 3.5 hours, and 9 lumens for 11 hours. Pretty incredible from a single AAA battery! Oh, and I recommend a lithium AAA battery because they run longer and are 1/3 lighter than other types of batteries. Normally I wouldn't care, but the reduced weight is surprisingly noticeable in something you'll have in your pocket all the time.

All these LED lights have one thing in common: batteries. It's unavoidable. Because you're a responsible geek, of course you use modern rechargeable battery technology. And as I wrote in Adventures in Rechargeable Batteries, sophisticated battery chargers are like geek catnip.

This is the LaCrosse BC1000 ($60), and it's a ton of fun to mess around with. Also, it recharges batteries. It might seem a little spendy, but it can do miraculous things like bring old nearly-dead rechargeable batteries back to life. And it comes with a bunch of actually useful accessories in the box:

• Nylon carrying bag
• 4 AA and 4 AAA rechargeable NiMH batteries
• 4 C size battery adapters
• 4 D size battery adapters

Yep, you can simulate C and D cells by putting the AA and AAA batteries inside the shells. The only battery type not represented here is the 9 volt. I own two of these LaCrosse chargers, and given the stupid number of AA and AAA powered devices in the house I'm thinking of buying a third. If you're a geek, you almost certainly have 99 battery problems, but armed with this baby, recharging ain't one. And don't forget the low self-discharge NiMH batteries, while you're at it.

Ah, the dremel. I think this Canadian forumgoer expressed it best:

It truly is hard for me to express the joy I feel when I am forced to break out the dremel; the last resort, the "Trojan Horse" of tools. In a dark place when all other tools abandon me and leave me heartbroken, the dremel always provides a loving shoulder to help complete my tasks. The dremel is a very selfless tool, he/she has no purpose to which they cling, yet is always willing to assist its fellow tools in completing theirs...

Drill strip a screw? The dremel can help... The jigsaw leave some nasty edges? dremel can restore them. I like to think of the dremel as the Jesus of tools.

They say Jesus performed many miracles and although it's not thoroughly documented, I believe his first miracle was, in fact, the dremel blueprint (he was a carpenter after all). The good Lord presented me with an image in a dream... I would like to share it.

If you don't own a dremel, I'm sorry, but I'm going to have to ask you to turn in your geek card. The dremel is truly the swiss army knife of DIY projects. Any DIY project.

I use my Dremel about once every few months, mostly for things that I probably shouldn't even be attempting. But that's the beauty of the Dremel. It doesn't judge; it just helps you get s**t done, by any means necessary. I don't recommend buying a big Dremel kit to start, because it's hard to tell which accessories you'll actually want or need until you begin using this insanely versatile tool. I suggest starting with the entry-level high power Dremel kit ($90).

Finally, I have to put in a mention for an updated version of what is probably the most frequently used thing on my keychain, with the biggest bang for the gram other than my front door key -- the Leatherman Squirt PS4 ($24).

That's right, you no longer have to face the terrible existential conundrum of choosing between pliers or scissors. The new PS4 model now includes both pliers and scissors. This is nothing less than a Christmas miracle, people! (Oh yeah, and get this awesome tiny carabiner to attach it to your keychain so you can easily detach it when you need to bust it out.)

So that's it this year. Nothing extravagant. Nothing too expensive. No frills. Just essential stuff I love and use regularly. I hope you, or someone you love, will love them too.

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

Fast Approximate Anti-Aliasing (FXAA)

Anti-aliasing has an intimidating name, but what it does for our computer displays is rather fundamental. Think of it this way -- a line has infinite resolution, but our digital displays do not. So when we "snap" a line to the pixel grid on our display, we can compensate by imagineering partial pixels along the line, pretending we have a much higher resolution display than we actually do. Like so:

As you can see on these little squiggly black lines I drew, anti-aliasing produces a superior image by using grey pixels to simulate partial pixels along the edges of the line. It is a hack, but as hacks go, it's pretty darn effective. Of course, the proper solution to this problem is to have extremely high resolution displays in the first place. But other than tiny handheld devices, I wouldn't hold your breath for that to happen any time soon.

This also applies to much more complex 3D graphics scenes. Perhaps even more so, since adding motion amplifies the aliasing effects of all those crawling lines that make up the edges of the scene.

But anti-aliasing, particularly at 30 or 60 frames per second in a complex state of the art game, with millions of polygons and effects active, is not cheap. Per my answer here, you can generally expect a performance cost of at least 25% for proper 4X anti-aliasing. And that is for the most optimized version of anti-aliasing we've been able to come up with:

1. Super-Sampled Anti-Aliasing (SSAA). The oldest trick in the book - I list it as universal because you can use it pretty much anywhere: forward or deferred rendering, it also anti-aliases alpha cutouts, and it gives you better texture sampling at high anisotropy too. Basically, you render the image at a higher resolution and down-sample with a filter when done. Sharp edges become anti-aliased as they are down-sized. Of course, there's a reason why people don't use SSAA: it costs a fortune. Whatever your fill rate bill, it's 4x for even minimal SSAA.

2. Multi-Sampled Anti-Aliasing (MSAA). This is what you typically have in hardware on a modern graphics card. The graphics card renders to a surface that is larger than the final image, but in shading each "cluster" of samples (that will end up in a single pixel on the final screen) the pixel shader is run only once. We save a ton of fill rate, but we still burn memory bandwidth. This technique does not anti-alias any effects coming out of the shader, because the shader runs at 1x, so alpha cutouts are jagged. This is the most common way to run a forward-rendering game. MSAA does not work for a deferred renderer because lighting decisions are made after the MSAA is "resolved" (down-sized) to its final image size.

3. Coverage Sample Anti-Aliasing (CSAA). A further optimization on MSAA from NVidia [ed: ATI has an equivalent]. Besides running the shader at 1x and the framebuffer at 4x, the GPU's rasterizer is run at 16x. So while the depth buffer produces better anti-aliasing, the intermediate shades of blending produced are even better.

Pretty much all "modern" anti-aliasing is some variant of the MSAA hack, and even that costs a quarter of your framerate. That's prohibitively expensive, unless you have so much performance you don't even care, which will rarely be true for any recent game. While the crawling lines of aliasing do bother me, I don't feel anti-aliasing alone is worth giving up a quarter of my framerate and/or turning down other details to pay for it.

But that was before I learned that there are some emerging alternatives to MSAA. And then, much to my surprise, these alternatives started showing up as actual graphics options in this season's PC games -- Battlefield 3, Skyrim, Batman: Arkham City, and so on. What is this FXAA thing, and how does it work? Let's see it in action:

No AA	4x MSAA	FXAA

(this is a zoomed fragment; click through to see the full screen)

FXAA stands for Fast Approximate Anti-Aliasing, and it's an even more clever hack than MSAA, because it ignores polygons and line edges, and simply analyzes the pixels on the screen. It is a pixel shader program documented in this PDF that runs every frame in a scant millisecond or two. Where it sees pixels that create an artificial edge, it smooths them. It is, in the words of the author, "the simplest and easiest thing to integrate and use".

FXAA has two major advantages:

1. FXAA smooths edges in all pixels on the screen, including those inside alpha-blended textures and those resulting from pixel shader effects, which were previously immune to the effects of MSAA without oddball workarounds.
2. It's fast. Very, very fast. Version 3 of the FXAA algorithm takes about 1.3 milliseconds per frame on a $100 video card. Earlier versions were found to be double the speed of 4x MSAA, so you're looking at a modest 12 or 13 percent cost in framerate to enable FXAA -- and in return you get a considerable reduction in aliasing.

The only downside, and it is minor, is that you may see a bit of unwanted edge "reduction" inside textures or in other places. I'm not sure if it's fair to call this a downside, but FXAA can't directly be applied to older games; games have to be specifically coded to call the FXAA pixel shader before they draw the game's user interface, otherwise it will happily smooth the edges of on-screen HUD elements, too.

The FXAA method is so good, in fact, it makes all other forms of full-screen anti-aliasing pretty much obsolete overnight. If you have an FXAA option in your game, you should enable it immediately and ignore any other AA options.

FXAA is an excellent example of the power of simple hacks and heuristics. But it's also a great demonstration of how attacking programming problems from a different angle -- that is, rather than thinking of the screen as a collection of polygons and lines, think of it as a collection of pixels -- can enable you to solve computationally difficult problems faster and arguably better than anyone thought possible.

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

Bias Lighting

I've talked about computer workstation ergonomics before, but one topic I didn't address is lighting. We computer geeks like it dark. Really dark. Ideally, we'd be in a cave. A cave … with an internet connection.

The one thing that we can't abide is direct overhead lighting. Every time the overhead light gets turned on in this room, I feel like a Gremlin shrieking Bright light! Bright light! Oh, how it burns!

But there is a rational basis for preferring a darkened room. The light setup in a lot of common computing environments causes glare on the screen:

If your room's lit, as most are, by fittings hanging from the ceiling, you'll be wanting to set up your monitor so that you don't see reflections of the lights in it. The flat screens on many modern monitors (like the excellent Samsung I review here) help, because they reflect less of the room behind you. And anti-reflective screen coatings are getting better and better too. But lots of office workers still just can't avoid seeing one or more ceiling fluoros reflected in their screen.

A good anti-reflective coating can reduce most such reflections to annoyance level only. But if you can see lights reflected in your screen, you can probably also directly see lights over the top of your monitor. Direct line of sight, or minimally darkened reflected line of sight, to light sources is going to give you glare problems.

Glare happens when there are small things in your field of vision that are much brighter than the general scene. Such small light sources can't be handled well by your irises; your eyes' pupil size is matched to the overall scene illumination, and so small light sources will appear really bright and draw lines on your retinas. The more of them there are, and the brighter they are, the more work your eyes end up doing and the sooner they'll get tired.

While a darkened room is better for viewing most types of computer displays, it has risks of its own. It turns out that sitting in a dark room staring at a super bright white rectangle is … kind of bad for your eyes, too. It doesn't help that most LCDs come from the factory with retina-scorching default brightness levels. To give you an idea of how crazy the defaults truly are, the three monitors I'm using right now have brightness set to 25/100. Ideally, your monitors shouldn't be any brighter than a well-lit book. Be sure to crank that brightness level down to something reasonable.

You don't want total darkness, what you want is some indirect lighting – specifically bias lighting. It helps your eyes compensate and adapt to bright displays.

"[Bias lighting] works because it provides enough ambient light in the viewing area that your pupils don't have to dilate as far. This makes for less eyestrain when a flashbang gets thrown your way or a bolt of lightning streams across the screen," he told Ars. "Because the display is no longer the only object emitting light in the room, colors and black levels appear richer than they would in a totally black environment. Bias lighting is key in maintaining a reference quality picture and reducing eye-strain."

Bias lighting is the happy intersection of indirect lighting and light compensation. It reduces eye strain and produces a better, more comfortable overall computing display experience.

The good news is that it's trivially easy to set up a bias lighting configuration these days due to the proliferation of inexpensive and bright LEDs. You can build yourself a bias light with a clamp and a fluorescent bulb, or with some nifty IKEA LED strips and double-sided foam tape. It really is that simple: just strap some lights to the back of your monitors.

I'm partial to the IKEA Dioder and Ledberg technique myself; I currently have an array of Ledbergs behind my monitors. But if you don't fancy any minor DIY work, you can try the Antec Halo 6 LED Bias Lighting Kit. It also has the benefit of being completely USB powered.

Of course, lighting conditions are a personal preference, and I'd never pitch bias lighting as a magic bullet. But there is science behind it, it's cheap and easy to try, and I wish more people who regularly work in front of a computer knew about bias lighting. If nothing else, I hope this post gets people to turn their LCD monitors down from factory brightness level infinity to something a tad more gentle on the old Mark I Eyeball.

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

On Parenthood

Our son was born March 12th, 2009. He's a little over two and a half years old. Now, I am the wussiest wuss to ever wuss up the joint, so take everything I'm about to say with a grain of salt – but choosing to become a parent is the hardest thing I have ever done. By far. Everything else pales in comparison.

My feelings on this matter are complex. I made a graph. You know, for the children.

That one percent makes all the difference.

It's difficult to explain children to people who don't yet have children, because becoming a parent is an intensely personal experience. Every child is different. Every parent is different. Every culture has their own way of doing things. The experience is fundamentally different for every new parent in the world, yet children are the one universally shared thing that binds our giant collective chain letter of human beings together, regardless of nationality and language. How do you explain the unexplainable?

Well, having children changes you. Jonathan Coulton likens it to becoming a vampire.

I was having a conversation with a friend who had recently become a parent, and she reminded me of something I had forgotten about since my daughter was born. She was describing this what-have-I-done feeling – I just got everything perfect in my life, and then I went and messed it all up by having a baby. I don’t feel that way anymore, but the thought certainly crossed my mind a few times at the beginning. Eventually you just fall in love and forget about everything else, but it’s not a very comfortable transition. I compare the process to becoming a vampire, your old self dies in a sad and painful way, but then you come out the other side with immortality, super strength and a taste for human blood. At least that’s how it was for me. At any rate, it’s complicated.

Maybe tongue in cheek, but not that far from the truth, honestly. Your children, they ruin everything in the nicest way.

Before Henry was born, I remembered Scott Hanselman writing this odd blurb about being a parent:

You think you love you wife when you marry her. Then you have a baby and you realize you'd throw your wife yourself under a bus to save your baby. You can't love something more.

Nuts to that, I thought. Hanselman's crazy. Well, obviously he doesn't love his wife as much as I love mine. Sniff. Babies, whatever, sure, they're super cute on calendars, just like puppies and kittens. Then I had a baby. And by God, he was right. I wouldn't just throw myself under a bus for my baby, I'd happily throw my wife under that bus too – without the slightest hesitation. What the hell just happened to me?

As an adult, you may think you've roughly mapped the continent of love and relationships. You've loved your parents, a few of your friends, eventually a significant other. You have some tentative cartography to work with from your explorations. You form ideas about what love is, its borders and boundaries. Then you have a child, look up to the sky, and suddenly understand that those bright dots in the sky are whole other galaxies.

You can't possibly know the enormity of the feelings you will have for your children. It is absolutely fucking terrifying.

When I am holding Henry and I tickle him, I can feel him laughing all the way to his toes. And I realize, my God, I had forgotten, I had completely forgotten how unbelievably, inexplicably wonderful it is that any of us exist at all. Here I am with this tiny, warm body so close to me, breathing so fast he can barely catch up, sharing his newfound joy of simply being alive with me. The sublime joy of this moment, and all the other milestones – the first smile, the first laugh, the first "dada" or "mama", the first kiss, the first time you hold hands. The highs are so incredibly high that you'll get vertigo and wonder if you can ever reach that feeling again. But you peak ever higher and higher, with dizzying regularity. Being a new parent is both terrifying and exhilarating, a constant rollercoaster of extreme highs and lows.

It's also a history lesson. The first four years of your life. Do you remember them? What's your earliest memory? It is fascinating watching your child claw their way up the developmental ladder from baby to toddler to child. All this stuff we take for granted, but your baby will painstakingly work their way through trial and error: eating, moving, walking, talking. Arms and legs, how the hell do they work? Turns out, we human beings are kind of amazing animals. There's no better way to understand just how amazing humans are than the front row seat a child gives you to observe it all unfold from scratch each and every day, from literal square zero. Children give the first four years of your life back to you.

I wasn't sure how to explain meeting new people to Henry, so I decided to just tell him we've met a new "friend" every time. Now, understand that this is not at all the way I view the world. I'm extremely wary of strangers, and of new people in general with their agendas and biases and opinions. I've been burned too many times. But Henry is open to every person he meets by default. Each new person is worth greeting, worth meeting as a new experience, as a fellow human being. Henry taught me, without even trying to, that I've been doing it all wrong. I realized that I'm afraid of other people, and it's only my own fear preventing me from opening up, even a little, to new people that I meet. I really should view every new person I meet as a potential friend. I'm not quite there yet; it's still a work in progress. But with Henry's help, I think I can. I had absolutely no idea my child would end up teaching me as much as I'm teaching him.

Having a child is a lot like running a marathon. An incredible challenge, but a worthwhile and transformative experience. It leaves you feeling like you truly accomplished something for all that effort. After all, you've created something kind of amazing: a person.

Bob: It gets a whole lot more complicated when you have kids.

Charlotte: It's scary.

Bob: The most terrifying day of your life is the day the first one is born.

Charlotte: Nobody ever tells you that.

Bob: Your life, as you know it... is gone. Never to return. But they learn how to walk, and they learn how to talk, and you want to be with them. And they turn out to be the most delightful people you will ever meet in your life.

It's scary and it's wonderful in equal measure. So why not have another baby? Or so we thought.

Turns out, we're having two babies. Both are girls, due in mid-February 2012.

I've been told several times that you should never be crazy enough to let the children outnumber you. I hope to ultimately win the War of the Lady Babies, but when it comes to children, I think all anyone can ever realistically hope for is a peaceful surrender.

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

Multiple Video Cards

Almost nobody should do what I am about to describe – that is, install and use more than one video card. Nobody really needs that much graphics performance. It's also technically complex and a little expensive. But sometimes you gotta say to hell with rationality and embrace the overkill.

Why? Battlefield 3, that's why.

I've been a fan of the series from the earliest days of Battlefield 1942, and I lost hundreds of hours to Battlefield 2 and Battlefield: Bad Company 2. I even wrote about the original Battlefield 2 demo on this very blog six years ago. So, yeah, I'm a superfan from way back. As much as I was anticipating Battlefield 3, I have to say the open beta convinced me it is everything I always wanted, and more. Glorious sandbox warfare on an enormous, next-generation destructible battlefield is a beautiful thing.

Since PC was the lead platform for Battlefield 3, it is the rare current game that isn't dumbed down to PS3 and Xbox 360 console levels; it is a truly next-generation engine designed to scale over the next few years of PC performance.

This also means it's going to be rough on current PCs; at a minimum, you'll need a fast dual core CPU, and a modern video card with 512mb or more video memory. It only goes up from there. Way up. Like most games, Battlefield 3 is far more limited by video card performance than CPU performance. This is normally the place where I'd trot out my standard advice urging you to buy one of the new hotness video cards released this holiday season. But unfortunately due to difficulties with the 40nm to 28nm process transition for ATI and NVIDIA, there aren't any new hotness video cards this year.

So what's a poor performance addicted Battlefield superfan to do? Double down and add another video card for more performance, that's what. Both ATI and NVIDIA have offered mature multi-GPU support for a few years now, and they've mostly settled on a simple Alternate Frame Rendering (AFR) strategy where each video card alternates between frames to share the graphics rendering work.

The little arrow there is a bridge attachment that you place on both cards so they can synchronize their work. Yes, there is a bit of overhead, but it scales surprisingly well, producing not quite double the performance but often in the area of 1.8x or so. Certainly enough to make it worth your while. You can technically add up to four video cards in this manner, but as with multiple CPUs your best bang for the buck is adding that second one; the third, fourth, and beyond provide increasingly diminished returns.

The good news is that the market crash in BitCoin GPU mining (if you don't know what this is, don't ask… please) means there is a glut of recent video cards up for sale on eBay right now. I have the same AMD Radeon HD 5870 that I've had since early 2010. I picked up another 5870 on eBay for a mere $170. This is a great video card, well ahead of its time when it was originally released, and even now only 10% slower than the fastest video card AMD makes. I simply dropped the second card in my system and installed the bridge connector.

You may recognize this computer as a further tweaked version of my last build (which is still awesome, by the way, and highly recommended). Anyway, for this to work, you'll need to establish a few things about your computer before rushing out and buying that second video card.

1. A motherboard that has two video card capable PCI Express slots. Most aftermarket and enthusiast motherboards have this, but if you bought a system from say, Dell, it's less clear.
2. A power supply with enough headroom to drive two video cards. Warning: modern gaming video cards are major power hogs -- they easily pull 100 to 200 watts under load. Each. Sometimes more than that! Be absolutely sure you have a quality power supply rated for a minimum of 600 watts. Each video card will have two power connectors, either 6 or 8 pin. Check that your power supply offers enough connectors, or that you have converters on hand.
3. A case with sufficient airflow to dissipate the 400 to 800 watts of CPU and GPU heat that you'll be generating. Understand that this is serious amounts of heat while gaming, way more than even the highest of high end PCs would normally produce. Yes, it is possible to do this quietly (at least in the typical idle case), but it will take some engineering work.

Beyond that, I found there are some additional peculiarities of multi-GPU systems that you need to be aware of.

• Make sure that the two cards you use are not only of the exact same family (minor vendor differences are OK) but also have identical clock and memory speeds. It's not supposed to matter, but I found that it did and I had to flash one of my cards to set it to default speeds to match the other card.
• Do not attempt to overclock your system while getting the multiple GPUs up and running. In particular, be extremely careful not to mess with the bus speed as timings are critical when dealing with two GPUs on the PCI Express bus synchronizing their work. Trust me on this one.
• Do a clean video driver remove and install the very very latest video drivers after putting the second card in. I recommend Driver Sweeper to remove any traces of your old drivers before rebooting.

Don't say I didn't warn you about this stuff, because I said it would be technically complex in the first paragraph. But after a (lot) of teething pains, I'm happy to report that multiple GPUs really does work as advertised. I can crank up games to the absolute maximum settings on my 27" monitor and get nearly constant 60 frames per second. As you can see in the below example, we go from 44 fps to 77 fps in Battlefield: Bad Company 2.

Now, Battlefield 3 (beta) is so very bleeding edge that I can't quite get it to max settings even with two GPUs in play. But I can now run very high settings, much higher than I could with a single GPU.

To be honest, it's unlikely I will continue with multiple GPUs through 2012 when the next-generation video cards are released. With every new video card introduction, you're supposed to get about the same performance in the new card as you did with two previous generation video cards working together. So at best this is a sort of sneak preview, cheating time by pretending we have a next-generation video card today. There are obvious efficiencies involved in performing that parallelization on a single GPU die rather than through two distinct video cards sitting on the PCI bus.

There's also the issue of micro-stuttering. I personally haven't found that to be a big problem unless you're pushing the graphics settings beyond what even two cards can reliably deliver. But if the frame rate dips low enough, the overhead of synchronization between the cards can interfere with overall frame rate in a perceptible way.

A single fast video card is always going to be the simpler, easier, and cheaper route. But multiple video cards sure is nifty tech in its own right, and it wasn't too expensive to get started with at $170. In the meantime, I'm having a ball playing with it, and I am dying to test my configuration with the final release of Battlefield 3 on October 25th. Join me if you like!

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

Serving at the Pleasure of the King

I enjoy my iPhone tremendously; I think it's the most important product Apple has ever created and one they were born to make. As a consumer who has waited far too long for the phone industry to get the swift kick in the ass it so richly deserved, I'm entirely on Apple's side here.

But as a software developer, I am deeply ambivalent about an Apple dominated future. Apple isn't shy about cultivating the experience around their new iOS products and the App Store. There are unusually strict, often mysterious rules around what software developers can and cannot do -- at least if they want entry into the App Store. And once you're in, the rules can and will change at any time. Apple has cracked down several times already:

• Prohibiting applications that include external mechanisms for purchases
• Prohibiting applications that have sexual connotations or innuendo
• Prohibiting applications with controversial satire
• Prohibiting applications that can potentially be used for unauthorized downloads

The developers involved are contractually prevented from even discussing specifically what happened to them by the terms of the app store. Those frustrating, inconsistent, opaque App Store experiences led developers to coin parodies such as Apple's Three Laws of Developers.

1. A developer may not injure Apple or, through inaction, allow Apple to come to harm.
2. A developer must obey any orders given to it by Apple, except where such orders would conflict with the First Law.
3. A developer must protect its own existence as long as such protection does not conflict with the First or Second Law.

It is absolutely clear who is in charge when you submit an application to the App Store. Apple developers serve at the pleasure of the king.

In Apple's defense, this is done in the name of protecting the consumers from malicious, slimy, or defective applications. Sort of like Nintendo's Seal of Approval, I guess.

The court of the king is a lucrative place to be, but equally dangerous. While upgrading my iPhone to iOS 5 – an excellent upgrade, by the way – I was surprised to discover the following blurb in the feature notes:

Safari Reader displays web articles sans ads or clutter so you can read without distractions. Reading List lets you save interesting articles to peruse later [like the popular Instapaper application], while iCloud keeps your list updated across all your devices.

Apple has since changed the page, but at the time I read it, there was a direct linked reference to Instapaper, the popular "save this webpage to read later" application which Reading List is a clone of. I distinctly remember this mention, because I was shocked that they would be so open and overt about replacing a beloved third-party application. Perhaps it made Apple uncomfortable too; maybe that's why they pulled the Instapaper text and link.

If Microsoft added a feature to Windows that duplicated a popular application's functionality, developers would be screaming bloody murder and rioting in the, er, blogs and web forums. But in the Mac world, if the king deems it necessary, then so it must be.

When iOS 5 and Lion ship, Apple will show a much larger percentage of iOS-device owners that saving web pages to read later is a useful workflow and can dramatically improve the way they read.

If Reading List gets widely adopted and millions of people start saving pages for later reading, a portion of those people will be interested in upgrading to a dedicated, deluxe app and service to serve their needs better. And they’ll quickly find Instapaper in the App Store.

I've met Marco Arment, the developer of Instapaper, and I like Marco. He's even been a guest on the Stack Exchange podcast. This is a nice, optimistic interpretation, but the reality is a little scarier. I'm struggling to understand why anyone would buy Instapaper when they can click a button in Safari and have that web page delivered to any of their Macs or iOS devices for later reading via iCloud.

Ah, but wait – what about offline support? Yes, that's something only Instapaper can deliver! Or can it?

A common scenario: an Instapaper customer is stocking up an iPad for a long flight. She syncs a bunch of movies and podcasts, downloads some magazines, and buys a few new games, leaving very little free space. Right before boarding, she remembers to download the newest issue of The Economist. This causes free space to fall below the threshold that triggers the [new iOS 5 space] cleaner, which — in the background, unbeknownst to her — deletes everything that was saved in Instapaper. Later in the flight, with no internet connectivity, she goes to launch Instapaper and finds it completely empty.

That's the problem with kings, you see. Their rule is absolute law, but they can be capricious, erratic, and impulsive. If you're lucky enough to live under the rule of a fair and generous king, then you'll do well. But historically speaking, monarchies have proven to be … unreliable.

I tend to agree with Marco that this is, in the big scheme of things, a minor technical problem. A private application cache not subject to iCloud syncing and space limitations would fix it. But it speaks volumes that Marco – a dedicated subject of the king – apparently had no idea this change was coming until it was on top of him. It's negatively impacting his Instapaper business and his customers. It's also concerning that this issue wasn't resolved or at least raised as a serious concern during the lengthy iOS 5 beta. Perhaps Apple's legendary secrecy is to blame. I honestly don't know.

As a consumer, I like that Apple is perfectly willing to throw its software developers under a bus to protect me (or, more cynically, Apple itself). But as a software developer, I'm not sure I can cope with that and I am unlikely to ever develop anything for an iOS device as a result. If you choose to deliver software in the Apple ecosystem, this is simply the tradeoff you've chosen to make. Apple developers serve at the pleasure of the king.

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.

The Gamification

When Joel Spolsky and I set out to design the Stack Exchange Q&A engine in 2008 -- then known as Stack Overflow -- we borrowed liberally and unapologetically from any online system that we felt worked. Some of our notable influences included:

• Reddit and Digg voting
• Xbox 360 achievements
• Wikipedia editing
• eBay karma
• Blogs and blog comments
• Classic web bulletin boards

All these elements were folded up into the Stack Exchange Q&A engine, so that we might help people create useful artifacts on the internet while learning with and among their peers. You know the old adage that good artists copy, great artists steal? That quote is impossible to source, but it means we were repurposing these elements we liked.

So, what do Picasso and T.S. Eliot mean? They say, in the briefest of terms: take old work to a new place. Steal the Google site, strip down what works (fast load, nonexistent graphics, small quirky changes that delight) and use the parts on your own site. Look at the curve of a Coke Bottle and create a beautiful landscape painting with it. Take the hairline pinstriping on the side of somebody’s car, reimagine it on your print job. Find inspiration in the world you live in, where nothing is truly new so that everything has the potential to be innovative.

Unfortunately, the elements we liked were often buried in mounds of stuff that we ... sort of hated. So extracting just the good parts and removing the rest was part of the mission. If you're lucky enough to have a convenient villain to position yourself against, that might be all you need.

Traditional web bulletin board systems have a design that was apparently permanently frozen in place circa 2001 along with Windows XP. Consider this typical forum thread.

Here is the actual information from that forum thread.

Based on the original size of those screenshots, only 18 percent of that forum thread page is content. The other 82 percent is lost to signatures, avatars, UI doohickeys, and other web forum frippery that has somehow become accepted as "the way things are done". I regularly participate in several expert niche bulletin boards of various types today, and they're all built the same way. Nobody complains.

But they should.

This is the status quo that we're up against. Yes, we fixed it for programmers with Stack Overflow, but why stop there? We want to liberate all the brilliant experts stuck in these horrible Soviet-era concrete block housing forums all over the web. We'd like to introduce them to the focused, no-nonsense Stack Exchange Way, a beautiful silo of pure Q&A signal without all the associated web forum gunk.

There's only one teeny-tiny obstacle in our way. As a great programmer I worked with once said:

It's the damn users. They've ruined every program I've ever created.

Every web forum is the way it is because users wanted it that way. Yes, the design of the forum software certainly influences behavior, but the classic 2001-era web forum paradigm assumed that what users wanted made sense for the rest of the larger internet. As it turns out, groups are their own worst enemy. What groups want, and what the rest of the world needs, are often two very different things. Random discussion is fine for entertainment, but it's not particularly useful, nor does it tend to generate the kind of artifacts that will be relevant a few years from now like Wikipedia does. So then the problem becomes how do you encourage groups to do what's best for the world rather than their own specific, selfish needs?

When I looked at this problem, I felt I knew the answer. But there wasn't a word for it in 2008. Now there is: Gamification.

Gamification is the use of game design techniques and mechanics to solve problems and engage audiences. […] Gamification works by … taking advantage of humans' psychological predisposition to engage in gaming. The technique can encourage people to perform chores that they ordinarily consider boring, such as completing surveys, shopping, or reading web sites.

I had no idea this Wikipedia article even existed until a few months ago, but we are featured prominently in it. It is true that all our stolen ideas about reputation systems, achievements, identity, and vote scoring are in place specifically to encourage the adoption of the brave new no-nonsense, all-signal Stack Exchange Q&A model. Without those incentive systems, when left to their own devices, what you get is … well, every forum ever created. Broken by design.

Yes, we have ulterior motives, but let me explain why I think gaming elements are not tacked on to the Stack Exchange Q&A engine, but a natural and essential element of the design from day one.

Learning is (supposed to be) fun

I've had this concept in my head way before the web emerged, long before anyone coined the term "Gamification" in 2010. In fact, I'd trace my inspiration for this all the way back to 1983.

For programmers, everything we know is pretty much guaranteed to be obsolete in 10 years if we're lucky, and 5 years if we aren't. It's changing all the time. The field of programming is almost by definition one of constant learning. Programming is supposed to be fun – and it is, if you're doing it right. Nobody taught me that better than the Beagle Bros on my Apple II. Why can't learning in every other subject matter be just as enjoyable?

Games are learning aids

There's a long, rich history of programmers as gamers. Oftentimes, the whole reason we became programmers in the first place is because we wanted to move beyond being a mere player and change the game, control it, modify its parameters, maybe even create our own games.

We used games to learn how to program. To a programmer, a game is a perfectly natural introduction to real programming problems. I'd posit that any field can use games as an introduction to the subject matter – and as a reinforcement to learning.

Games help people work toward a goal

It's something of a revelation to me that solid game design can defeat the Greater Internet F**kwad Theory. Two great examples of this are Counter-Strike and Team Fortress. Both games are more than ten years old, but they're still actively being played right now, by tens of thousands of people, all anonymous … and playing as cohesive teams!

The game's objectives and rules are all cleverly constructed to make working together the most effective way to win. None of these players know each other; the design of the game forces players to work together, whether they want to or not. It is quite literally impossible to win as a single lone wolf.

I haven't ever quite come out and said it this way, but … I played a lot of Counter-Strike from 1998 to 2001, and Stack Overflow is in many ways my personal Counter-Strike. It is a programmer in Brazil learning alongside a programmer in New Jersey. Not because they're friends -- but because they both love programming. The design of Stack Overflow makes helping your fellow programmers the most effective way to "win" and advance the craft of software development together.

And I say we all win when that happens, no matter which profession we're talking about.

I feel a little responsible for "Gamification", since we're often cited as an example (even, much to my chagrin, on Wikipedia). I wanted to clear up exactly why we made those choices, and specifically that all the gaming elements are there in service of a higher purpose. I play the Stack Exchange game happily alongside everyone else, collecting reputation and badges and rank and upvotes, and I am proud to do so, because I believe it ultimately helps me become more knowledgeable and a better communicator while also improving the very fabric of the web for everyone. I hope you feel the same way.

(If you'd like to learn more about the current state of Gamification, I highly recommend Sebastian Deterding's page, and specifically his Meaningful Play: Getting Gamification Right presentation.)

[advertisement] What's your next career move? Stack Overflow Careers has the best job listings from great companies, whether you're looking for opportunities at a startup or Fortune 500. You can search our job listings or create a profile and let employers find you.