What could cause the cigarette lighter to stop working?

Cigarette lighter not work?I read in my car owner manual, and it tells me that the reason why a cigarette lighter will stop working is because the heating mechanism is burned out. I'm not sure exactly what it is or what is a definite answer for why it would burn out. But one reason was given. It said if you take the lighter out before it pops up, that it would cause the heating mechanism to burn out faster.