Look at your screen right now. What do you see?
If you design software you'll see things like:
What our users see
a piece of glass with glowing shapes on it.
We who work in designing software products are exposed to UI in high doses. This warps our perception. Those shapes on the screen are *meaningful* to us at many levels:
Our users? Their interest is highly focused on *what they want out of their computer* and not on the underlying semantics of the UI technology that is blasting shapes onto that piece of glass.
Keep that in mind the next time you think about the usability of your UI. Is the UI really as *obvious* as you think it is?