Bad usability in the design of aircraft controls can result in what is cheerfully referred to as CFIT: Controlled Flight Into Terrain.

The usability of your product may not be quite as critical. If you’re lucky, the mistakes you make in usability design will merely cause people to lose limbs, or, heck, even just thumbs. No biggie!

In fact if you’re extremely lucky, your unusable design will do nothing more than make people sad. They’ll try to accomplish things, and either fail, or struggle, and for very real reasons this will literally make them unhappy. I’ll explore the psychological reasons for that in a future article, but for now, suffice it to say that making the users of your design unhappy is not likely to be precisely the result you were looking for, unless you’re designing a French film.

So, usability. That’s really at the heart of good design, and I’m going to spend a lot of time on it.

The good news is that I can teach you everything I know about usability while standing on one foot. Ready? Here we go:

Something is usable if it behaves exactly as expected.

That’s it! That’s the whole story! As Hillel said, all the rest is commentary.

Let me run a little example by you.

Which is Easier to Use: Windows or Mac?

When you’re designing a product for humans, it helps to keep imaginary users in mind. The more realistic the imaginary user is, the better you’ll do thinking about how they use your thing.

My imaginary user is Pete.

Pete is an accountant for a technical publisher who has used Windows for six years at the office, and a bit at home. He is fairly competent and technical. He installs his own software; he reads PC Magazine, and he has even programmed some simple Word macros to help the secretaries in his office send invoices. He has a cable modem at home. Pete has never used an Apple Macintosh. “They’re too expensive,” he’ll tell you. “You can get a 3.6 GHz PC with 2 gigs of RAM for the price of…” OK, Pete. We get it.

One day Pete’s friend Gena asks him for some computer help. Now, Gena has a Macintosh iBook, because she loves white computers. When Pete sits down and tries to use Gena’s Macintosh, he quickly gets frustrated. “I hate these things,” he says. He is, finally, able to help Gena, but he’s grumpy and unhappy. “The Macintosh has such a clunky user interface.”

Clunky? What’s he talking about? Everybody knows that the Macintosh has an elegant user interface, right? The very paradigm of ease-of-use?

Well.

On the Macintosh, when you want to resize a window, you have to grab the bottom right hand corner to resize it. On Windows, you can resize from any edge. When Pete was helping Gena, he tried to widen a window by dragging the right edge. Frustratingly, the whole window moved, rather than resizing as he expected.

On Windows, when a message box pops up, you can tab to a button and hit the space bar to press that button. On the Mac, space doesn’t work. When Pete got alerts, he tried to dismiss them using the space bar, like he’s been doing subconsciously for the last six years.

The first time Pete tried that on the Mac, nothing happened. Without even being aware of it, Pete banged the space bar harder, since he thought that the problem must be that the keyboard did not register his tapping the space bar. Actually, it did—but it didn’t care! Eventually he used the mouse. Another tiny frustration.

Pete has also gotten into the habit of using Alt+F4 to close windows. On the Mac, this actually changes the volume of the speakers. At one point, Pete wanted to click on the Internet Explorer icon on the desktop, which was partially covered by another window. So he hit Alt+F4 to close the window and immediately double-clicked where the icon would have been. The Alt+F4 raised the volume on the computer and didn’t close the window, so his double click actually went to the Help button in the toolbar on the window which he wanted closed anyway, and that immediately started bringing up a help window, slowly, so now, he’s got two windows open which he has to close.

Another small frustration. But, boy, does it add up. At the end of the day, Pete is grumpy and angry. When he tries to control things, they don’t respond. The space bar and the Alt+F4 key “don’t work”—for all intents and purposes, it’s as if those keys were broken. The window disobeys him when he tries to make it wider, playing a little prank where it just moves over instead of widening. Bad window. Even if the whole thing is subconscious, the subtle feeling of being out of control translates into unhappiness. “I like my computer,” Pete says. “I have it all set up so that it works exactly the way I like it. But these Macs are clunky and hard to use. It’s an exercise in frustration. If Apple had been working on MacOS all these years instead of mucking about with video iPods and other toys, their operating system wouldn’t be such a mess.”

Right, Pete. We know better. His feelings come despite the fact that the Macintosh really is quite easy to use—for Mac users. It’s totally arbitrary which key you press to close a window. The Microsoft programmers probably thought that they were adding a cool new feature by letting you resize windows by dragging any edge. The Apple programmers probably thought they were adding a cool new feature when they let you move windows by dragging any edge.

All those flame wars you read on the OS bigot websites about user interface issues focus on the wrong thing. Windows is better because it gives you more ways to resize the window. So what? That’s missing the point. The point is, does the UI respond to the user in the way in which the user expected it to respond? If it didn’t, the user is going to feel like they can’t control the interface, and they’re going to be unsuccessful. That’s all there is to it. Something is usable if it behaves exactly as expected. Tattoo this on your forehead. Backwards, so you can read it in the mirror.

If you follow along in future articles, you’ll see that just about everything I can teach you about usable design is going to relate back to this simple rule, so if for some reason aliens land in your garden tonight and whisk you away to the planet Kij8zxwrk, where you have no access to the Earth’s Internet because TCP/IP doesn’t work well when packets take hundreds of years to arrive, you already know enough to get a job as a pretty decent usability designer.

Articles in gray are still being written. Many of these articles are derived from chapters in User Interface Design for Programmers.

(* = first draft)

Introduction

Introduction to Great Design*
What is Design?*
What Makes It Great?*

Good Design

User Model vs. Program Model
Choices
Affordances and Metaphors
Broken Metaphors
Consistency and Hobgoblins
Modes
Put users in control
Design for Extremes
Users don’t read
Users can’t control the mouse
Users can’t remember anything
Activity Based Design
Usability Testing
Relativity (UI Time Warps)
How Do It Know?
Tricks of the Trade
UIs that Kill
Beta Testing
The Onion in the Varnish
Information Design / Answering the Right Question
Shipping is a Feature

Great Design

Introduction to Black Magic of Great Design
Aesthetics
Emotional Design
Designing the Social Interface
Building Communities
Obsessive Attention to Detail
Taking Things Away
Playing with Fire (making things worse)
User happiness vs. user success

Now that we’ve more-or-less defined “design,” since the working title of this series is Great Design, I better come up with a working definition of “great.”

Just about every product category has its blue-chip, gold-plated stars. Movie stars? Brad Pitt. Best rock song of all time? Sweet Home, Alabama, of course. Office chairs? The Herman Miller Aeron. Portable MP3 players? Clearly the Apple iPod.

What do these products have in common?

Brad Pitt can attract millions of people to the box office. He’s very good looking, and very charismatic, and it’s not even clear if he can act, but who cares?

Sweet Home, Alabama is one of the catchiest songs of all time. It’s extremely popular despite the fact that it’s impossible to sing or hum (the refrain requires harmony), the melody is awkward, and the lyrics include a couple of reprehensible lines defending Alabama’s racist and segregationalist governor George Wallace, but few people really notice the flaws, they just enjoy the song.

The Aeron chair became the symbol of high end office chairs. It’s expensive and looks like a giant cockroach, but when the directors of 24 need to show the canonical “super luxury office chair” for the White House, they use an Aeron.

And finally, the iPod. Ah, the iPod. It’s way more expensive than any competitive MP3 player. It has fewer features than the competition. The iPod nano, the tiny one that everybody’s raving about, is the only product I’ve ever seen that can be scratched beyond all recognition just by touching it lightly with your finger, and the shiny mirror back will be permanently covered in greasy fingerprint smudges from the moment you take it out of the elegant package until the battery wears out and you have to throw away the whole thing and buy another. But who cares?

The blue chip product in every category can usually be thought of as being popular despite obvious design flaws. Weird.

As the design gets better and better, as the product becomes more and more suitable to its users needs, it becomes more likely to be chosen by customers. So the 40GB MP3 player, all else being equal, will outsell the 20GB MP3 player. The easy-to-use phone will outsell the hard-to-use phone. All else being equal. That part is not weird.

But that only gets you so far, as Creative, makers of the unloved ZEN MP3 players, are learning the hard way. Despite having products that are better than the iPod by just about every reasonable metric, they are unable to even come close to Apple iPod’s dominant market share. They’re cheaper. They have more memory. They support more file formats. Etc. Doesn’t matter: they still have single-digit market share while iPod is probably in the 80s somewhere.

That’s because good design can only take you so far. Getting every aspect of the design perfect, making a usable product, making the right tradeoffs between price and functionality, between flexibility and ease of use, between weight and battery life, etc., etc., etc., is all really important, but the most it can possibly get you is to #2.

It’s like beauty. A wannabe model can be tall, with a perfectly symmetrical face, beautiful skin, lovely eyes, and perfectly straight white teeth, and still be considered unattractive. On the other hand, you can have a gigantic broken nose, or be completely lacking in eyebrows, or have a giant gap between your two front teeth, and still be People Magazine’s Sexiest Whatever of the Year.

How do you get to be #1? That’s the mystery here. And since certain markets (graphical operating systems, online auctions, and apparently MP3 players) seem to be winner-take-all markets, being #2 or #3 may not be good enough.

So this is what I’m talking about when I say “Great Design.” It’s that ineffable quality that certain incredibly successful products have that makes people fall in love with them despite their flaws. It’s extremely hard to pull off. I sure as heck can’t do it. But, if you bear with me, I think I have some theories as to what’s happening. While these theories do not exactly add up to a recipe for making good products into great products, they may give you a clue as to what’s going on when people go crazy about the Aeron chair or Julia Roberts.

Here’s the overall plan for this series of articles. First, I’m going to go through good design, namely, all the things you should know to get your design adequate given the current state of the art. Ease of use is a fundamental part of that so I’ll spend a lot of time on usability.

Later, once I’ve got all the obvious things taken care of, you’ll have a really usable design and one which meets your customers’ needs, and in fact, if you pay more attention to these usability things than your competitors, you may have the best design, but that’s not going to get you to #1.

“Every time I read Jakob Nielsen,” I wrote in 2000, “I get this feeling that he really doesn’t appreciate that usability is not the most important thing on earth. Sure, usability is important (I wrote a whole book about it). But it is simply not everyone’s number one priority, nor should it be. You get the feeling that if Mr. Nielsen designed a singles bar, it would be well lit, clean, with giant menus printed in Arial 14 point, and you’d never have to wait to get a drink. But nobody would go there; they would all be at Coyote Ugly Saloon pouring beer on each other.”

So in the final articles, roughly the last third of the series, I’ll peek under the covers at the black magic of great design. You may not be able to pull it off. It takes real talent, not just hard work. But at least I hope you’ll recognize some of the things that are going on that make certain gadgets, software, songs, movie stars, and office chairs make that leap from merely throroughly good to truly and significantly great.

Note

I’ve put up a very high-level index of the articles in this series. The list of upcoming articles may change and be rearranged a bit by the time I get there, and I may not deliver them all in order, but this is the general, big picture outline of what’s coming. You may recognize many of the chapters from the online edition, or the longer printed edition, of User Interface Design for Programmers. Those chapters will be expanded, updated, and reevaluated but the key ideas will remain the same.

The paragraph about Sweet Home Alabama has been reworded since I posted it yesterday.

Confession: I’m afraid to turn off my cell phone.

Not because I’m afraid of being out of touch, mind you. Heck, I could care less if people can reach me. If you have something to tell me that’s so important it would be worth interrupting Will and Grace, well, I think I’d rather have another 45 minutes of ignorant bliss before I find out about it. That’s my motto: Will and Grace First, Earthquakes and Floods Later.

Here’s why I’m afraid to turn off my cell phone: because I can’t always seem to muster the brain cells necessary to turn it back on.

It has two buttons on it, a happy green button and a scary red button. They have funny icons on them that don’t mean very much to me.

You might think that the green button turns it on. Green means go, right?

Wrong.

I tried that. Nothing doing. I tried pressing and holding the green button, because sometimes these phones want you to press-and-hold so that you won’t accidentally take a picture of your ear, or disconnect the phone call in the middle of an important job interview, or whatnot.

It turns out it’s the red button that turns it on.

When you press the red button, usually, nothing actually happens, so you suspect you might have done something wrong.

It turns out that you have, actually, turned on the phone, and if you’re in a dark room, you would have noticed that the keyboard flashed when you turned it on. In a bright room, nothing happens for six seconds. That’s usually long enough to think that you’ve done something wrong. So that’s when I start trying the other buttons, like the happy green button. In any case, I wind up feeling frustrated and not in control of my life.

Once you do learn that the red button turns the phone on, and you don’t have to hold it, you start to get frustrated that the time it takes the phone to boot up and load the pretty background picture and get on the network is something like 30 seconds. That’s frustrating, too. It seems like in the Olden Days you didn’t have to wait for half a minute to turn on an appliance. There was a switch, up was on (unless you lived in Europe, where they had a terrible war and couldn’t afford appliances), you switched it, the thing went on and started spinning or shining or whatever it is that the thing was supposed to do. Instantly. End of story.

Indeed, it’s surprising just how many of today’s devices and gadgets and remote controls have actually made TVs, stoves, and telephones harder to use. Suddenly, bad computer user interface design is seeping into the entire world.

Six years ago, with the total dominance of the consistent GUI interface of Mac and Windows, it seemed like the state of the art in software UI design was getting pretty good. Nothing fabulous, mind you, but pretty good. You could sit down with a new Windows app that you’d never seen before and have a pretty good chance of being able to operate it correctly.

That’s when I wrote a book called User Interface Design for Programmers, thinking, great! It’s time to get everybody on the same page here on how to design user interfaces, and then life will be wonderful.

Unfortunately, that was about the same time as there was a huge wave of new consumer gadgets, and, of course, that web thing hit us.

The web didn’t really have a standard UI. You could make anything be a link. We didn’t have dropdown menus, so we made do with all kinds of differently-behaved simulations of dropdown menus.

Gadgets? Gadgets were even worse. They had tiny keyboards and tinier screens. Combined with rampant featuritis, these damn devices did more and more things but just figuring out how to do them took a degree in engineering (or a bright 12 year old, but slavery has been abolished, especially for 12 year olds.)

Maybe nobody told the people who design gadgets and gizmos and websites (and even software) that they need to work on their user interface skills.

So, this is their wake up call.

While most products were became increasingly incomprehensible, like the typical home entertainment remote control, with dozens of mushy little buttons marked “MTS” or “SURR” or “PTY” that nobody has any hope of understanding, something else was happening: a very few, very good designers were, somehow, coming up with truly great designs that were beautiful, easy to understand, fun, and which made people happy. You know who they are because those products became bestsellers. The Apple iPod. TiVo. Google. Even the Motorola RAZR, which is so hard to turn on, is, in most ways, a great design.

Over the next weeks and months, if all goes well, I’m going to write a series of articles right here, on this website, on UI design for the modern age. The whole series will be, tentatively, named Great Design.

If all goes well, we’re going to look at some of the original principles of good UI design, much of which I covered in the first book, and revisit them and see how they apply to today’s world of miniature gadgets, websites, and street-corner garbage cans.

Then, if we’re really lucky, we’re going even farther. We’re going to look at what it takes to make the leap from a servicable, decent product design to a Mindbogglingly Great, Earth-Shaking, History-Changing product design. I have some theories about that, too.

Administatrivia

First, one change that you’ll notice. I’m going to publish each article twice. The first appearance will be a rough draft. Later, I’ll revise and edit the article, taking into account some of the feedback I received, and republish it as a second draft. I’m doing it this way because it lets me publish something almost as soon as I’ve written it, without too much editing, secure in the knowledge that I can edit it to death later.

There are three ways to follow along:

1. Come back to www.joelonsoftware.com regularly
2. Subscribe to the Joel on Software RSS feed with your favorite feed reader (I like Bloglines, personally, but there are heaps)
3. Or get an email subscription by entering your email address at the bottom of the page.