part three

user interface design is rarely about designing pretty widgets, it's about making usable widgets. the trick is anticipating the user's movements: understanding the user's intent makes user interface design easier because their moments are no longer ambiguous, they follow a prescribed path.

another way to think of the following statements:

• what can it do?
• what is it for?

the first is obvious. for most anything, you can usually see what it does by looking at it or watching it in action. the second is not obvious because it explains a relationship between the object and its user. in some rare cases, knowing what something does may suffice, but more often than not, we ask what something is good for.

i give you a laptop. what's it do? it can perform billions of calculations a second and store information on a spinning metal platter! what's it for? mobile blogging? image manipulation? programming? but often its use has nothing to do with what it actually does. the laptop is a usable interface to a hard drive, cpu and other technological niceties.

However, considering what a computer can do, it's strange that most calculator programs that come with them can often do very little. Or for that matter, why it is difficult for me to easily record the output of my screen to a movie file. Half of the computer's ability lies in storage, but i am somehow unable to harness that power myself. By decoupling intent from ability, we avoid asking these questions.

i sit you in a classroom, we're learning about fractions today. what do they do? well, they don't do anything really. what are they for? well, we can have 'one third of a pizza.' or we can use fractions as a way to express a ratio, 'thirteen miles per hour.' let's learn how to add them or subtract them!

wait, i lied, fractions actually do something. but what is it? does it have anything to do with math? does it always?

understanding one half of 'what does it do' versus 'what is it for' puts you in a strange situation. You may have technical mastery of a subject but never know why it works. similarly, you may understand the theory but you may never have technical skill. the reason for teaching one over the other is clear, although unsettling.