Usability is a term used to denote the ease with which people can employ a particular tool or other human-made object in order to achieve a particular goal. Usability can also refer to the methods of measuring usability and the study of the principles behind an object’s perceived efficiency or elegance.
Usability usually pertains to how efficiently a product (or software, or just about anything) can be used, how easily one can learn to use it, and how satisfying it is. So you can imagine your favorite gadget to be usable if it satisfies these three criteria–that is, if you were easily able to learn how to work it, and if you’re satisfied overall.
Simplicity: a concept in itself, and not a lack of something else
Many people equate usability to simplicity, and I cannot help but agree. Something usable should be simple enough to use that you shouldn’t have to RTFM. However, this does not mean something should be dumbed down and feature-less. To better illustrate, let me cite what Joel Spolsky writes on his blog.
Devotees of simplicity will bring up 37signals and the Apple iPod as anecdotal proof that Simple Sells. I would argue that in both these cases, success is a result of a combination of things: building an audience, evangelism, clean and spare design, emotional appeal, aesthetics, fast response time, direct and instant user feedback, program models which correspond to the user model resulting in high usability, and putting the user in control, all of which are features of one sort, in the sense that they are benefits that customers like and pay for, but none of which can really be described as â€œsimplicity.â€ For example, the iPod has the feature of being beautiful, which the Creative Zen Ultra Nomad Jukebox doesn’t have, so I’ll take an iPod, please. In the case of the iPod, the way beauty is provided happens to be through a clean and simple design, but it doesn’t have to be. The Hummer is aesthetically appealing precisely because it’s ugly and complicated.
So Joel says that aesthetics is a matter of taste. The iPod’s elegance lies in its simplicity. However, other objects may be beautiful because of how complicated they are. Just like mechanical watches, with all the gears, cogs, tourbillons, and whatnot. However, Joel goes on to say that the concept of simplicity does not mean you have to take out features to make something usable.
I think it is a misattribution to say, for example, that the iPod is successful because it lacks features. If you start to believe that, you’ll believe, among other things, that you should take out features to increase your productâ€™s success. With six years of experience running my own software company I can tell you that nothing we have ever done at Fog Creek has increased our revenue more than releasing a new version with more features. Nothing.
Strike a balance
However, I would like to disagree to some extent. Too many features might just confuse users. And actually Joel wrote about that just recently, when he posted about Windows Vista’s having too many shutdown options. So I guess it has to be a balance in design. Something should have enough features, but useful features. And the product’s design should be simple enough not to give the common end-user headaches having to wade through tons of features, but also intelligent enough to be able to give the more advanced ones access to the extended feature set.
It’s just like OS X having a straightforward UI for everybody, but access to the terminal for advanced users who want to tweak just about everything.
It’s a complicated concept to think about, I know, but being an end user I appreciate elegance in design. That’s why I work better on my old PowerBook than my newer, supposedly faster Compaq Presario. That’s why I went for the iPod Video when there are other, cheaper MP3 players that can do much more. It’s about efficiency, elegance and satisfaction.
It’s that simple.