Poker tournaments, especially where the game is Texas hold 'em, have become very popular the last few years (2002-2004) with the advent of the high level tournaments becoming televised and the creation of the World Poker Tour. While a tournament plays much like a normal poker game, there are a number of differences between a normal money game and a tournament game.
The most important difference is that everyone starts with exactly the same amount of money, with exceptions. Some tournaments offer re-buys, which allow players to buy more chips at various stages of the tournament. These re-buys are generally limited to a set amount and only offered at set times during the tournament. Also, players are generally given chips that are non-negotiable outside of the tournament, and the amount their chips are worth during the game has no relation to the buy-in amount.
Another difference in tournaments is a schedule for the raising of the blinds or bring-in amounts. A tournament where competitors sit down with 1000 units of chips may start with 7/15 blinds, escalates to 10/20 after 10 hands, then 15/30 after another 10, then 25/50, 50/100, and so on. Since the players' average chip stack increases as players are elminated, this keeps the size of the stakes roughly equivalent throughout.
Only 9 or 10 people can fit at one table, so most scheduled tournaments are generally of the multi-table variety. When a set number of people have been eliminated, the organizers will consolidate the remaining players to a smaller number of tables. Play continues until one player has all the chips, with short breaks every few hours.
There are also what are known as "sit-and-go" tournaments, in which play starts once the table has been filled. Additional players wishing to play start at another table and wait for that one to fill. Each table is its own separate tournament; the tables are never consolidated, and the prizes are not spread among them.
As to the prizes, sit-and-go tournaments generally award prizes to the top 3 players. A typical arrangement is half the prize to first, three-tenths to second, and the remaining one-fifth to third. In multi-table tournaments, how far the prizes go down and what percentage eachplace wins depends on the number of players and schedules vary between organizers. Since the number of players at multi-table open tournaments is unknown when the schedules are determined, the numbers are generally not very round.
The buy-in amounts for tournaments are announced in the $X + $Y format, where $X goes into the prize pool, and $Y goes to the organizers in order to cover the costs of running the tournament. The additional cost is usually in the area of 10% the contribution to the prize pool.
There are two changes in the formats of tournaments that are the basis for players' strategy tweaks. The first is that players must play until they lose all their chips (or win the whole thing); they cannot decide to cut their losses short if they aren't doing well. The second is related to the first in that players aren't playing strictly for money, but for finishing position. The superior plays are those that allow one to stay in long enough to see more players drop out, rather than those that make the most money in the long run.
Poker tournaments can be found online at any of the zillions of internet poker rooms. Some even offer tournaments with no entry fees that give out real money (as opposed to demo or fake money) in order to entice you to deposit money with them. Most will offer satellites into tournaments with larger buy-ins, the most celebrated being those that offer slots into the World Series of Poker. In a bit of validation for online poker players, the 2003 WSOP champion, Chris Moneymaker, won his $10,000 buy-in winning a $40 online satellite.
Tournament style poker is not the favorite of many poker pros, who prefer money games where they can take a theoretically unlimited amount of money from suckers who are unfortunate and/or dumb enough to play with them. They also can dig deep into their pockets in case they have a bad run of cards after figuring out tells for most the table, where a similar situation in a tournament would force them out and unable to use the information.
machfive notes that some tournaments go so far as to award a winning to only the final standing individual.