Anatomy of Type

And that's what I'll tell you about today: fonts. Why isn't there just one universal font that is used in everything from books to billboards? 1: That would be very boring. 2: Like color, fonts have hidden personalities. If people use the wrong fonts all the time, life would be a nightmare. Think about this: You go get a job application for something very professional, like a lawyer. But the entire application is printed in Comic Sans *gasp*. Everyone in the room is now wearing clown noses, party hats, and too much makeup. You are embarrassed as they laugh hysterically at you for no particular reason.
Yes, that is an over-exaggeration. Still, you would think the paper is stupid, because Comic Sans isn't a professional font. So don't fill out an application written in it, because your employers are proving themselves to be...well, stupid.
So this moral: Pay attention to what fonts are saying and choose the right ones for the right things.