To join in in a Multi table tournament (MTT) you must pay a Buy-In and a fee. The prize pool arises from the Buy-Ins and the supplier/operator keeps the fee for organizing the event of the tournament. The Buy-Ins rank from $0 up to several $1000. For the Buy-In one gets a certain number in chips. However, differently than with the Cash Game the chips have no direct cash value, cannot be exchanged for cash. One calls these chips, hence, also tournament chips and shortens them often from with $T or € of T.
The tournament starts at an agreed time. First all registered players are distributed to the different tables. Some MTTs are played at tables with ten places (10-handed), some at nine-tables (9-handed), at six-tables (6-handed) or even at Heads Up tables with only two players per table. As soon as a player eliminates all his chips from the tournament by the loss, his place is taken as fast as possible by the supplier with a new player of another table. In this manner the number of the tables decreases in the course of a tournament continuously because tables are dissolved and the players are distributed to free-become places.
At the beginning of a MTTs the Blinds are very small in contrast to the number in chips which you get. However, after a before agreed time interval the Blinds and with it the pressure on you and your chips increase. Since as soon as the Blinds increase, you must pay necessarily more. You should pay attention always to the fact that you win enough chips not to be eaten up formally by the Blinds.
The players who lose all her chips retire and the number of the participants thereby decreases, still during the tournament are constant. At the end the winner of the tournament holds all chips and gets for it the biggest part of the prize money.
Depending on how many participants will register itself for a tournament the prize pool in terms of percentage split. Mostly there are for 10 %-15 % of the participants money to win. The players who create it just so still in the monetary ranks get back as a rule only a little bit more than the Buy-In. However, the winner of the tournament fills full 25%.
Basically there are two different kinds of MTTs. The difference lies in whether a player must retire after the loss of all chips or whether he may buy a place again:
If a player retires immediately if he has lost all chips one speaks of a Freezeout tournament.
With a Rebuy/Add-On tournament one can buy a place against it after the loss of his stack anew. During the Rebuy phase it is often possible to effect so many Rebuys like one wants. Of course one pays for it over and over again the original Buy-In. At the end of the Rebuy phase there is for all players once again the chance an Add-On to shop with which every player gets additional chips to his stack.

