Two related concepts you hear about endlessly in UI design are affordances and metaphors. These are just ways to bring the user model in line with the program model by giving the user little clues about how the program works and what they’re supposed to do with it.

Read more in Chapter 4 of UI for Programmers.

About the author.

I'm Joel Spolsky, co-founder of Trello and Fog Creek Software, and CEO of Stack Overflow. More about me.