Heaven is a fairly common religious concept. It is allegedly a place you "go" when you die, if you meet certain conditions in your period on earth. The conditions vary depending on the religion. Some religions require that you do not break their strict moral rules, some require that you lead a "good life" as definded by the religion, some require large donations of your time/money to their cause, and some simply require that you believe what they tell you (this one is the most silly. In Christianity if you simply believe Jesus is God, that qualifies you for admission into heaven).

Heaven is an incentive. It is used to lure people into following the rather controlling rules set by religions. If you do as they tell you here on earth, when you die you get a reward. You will go to a place of perfection, where you will have eternal happiness and pleasure. However if you disobey the rules stated you will be damned to hell, a place of misery, where you will have eternal suffering and pain.

I must say whoever came up with the whole concept of heaven is a genius. What better way could there be to lure people to follow you than by promising them a reward when their dead? There is no way to prove them wrong! The hell part is even better. What better could there be way to scare people into following you than to warn them that not following them will lead them into eternal suffering? The Catholic church is especially good at using this control method to exploit its followers. "Sure your life may be miserable on earth, but if you do everything we tell you, after you die you will be eternally happy. Not lisening to us will result in eternal suffering." A very effective scare tactic. If what they say is true, you don't really have much of an option other than to blindly follow.

Personally, I don't think going to heaven would be that great anyways. I mean what are you really going to do for eternity? What do people in heaven do? Sit around and play cards? It sounds boring.