There are many times of poker tournaments, but the most popular and typical tournament type is the freezeout, meaning that once someone lost all chips he is eliminated. This tournaments structure is quite simple: you place the buy-in, you start with the same amount as others, then the blinds begin to increase slowly and players get eliminated as they lose all their chips. The prices are given to the top winners, that means to less than 10% of the players in happy cases (sometimes it doesnt even mean 1%).
But aside this type of tournaments you can also find tournaments that allow further re-buys or add-ons. In these tournaments if you lose all your chips then you can re-buy, paying the same amount you paid initially and receiving the same amount of chips as you did first. Usually the re-buy can be made for a certain period of time after the tournament began. After this period has passed, you cannot re-buy, so if you lose all your chips you will be eliminated. But you can pay to add a certain amount of chips to your stack whenever you feel it is necessary.
There also are the turbo tournaments that basically increase the blinds every five or even two minutes. If you...