The minimum amount of a raise is equal to the amount of the previous raise - not the amount of the previous bet. Let's assume that the blinds are 100 and 200 and that the opener raises to 600. If the next player wants to re-raise, then the minimum re-raise is now TO 1,000. Because the previous raise was 400. This rule causes confusion because many people incorrectly believe the raise amount was 600 and that the minimum raise is now TO 1,200. This is because they are used to playing limit where the raise is always equal to double the previous bet.
A player can only win from each player as many chips as he bets. This is called a main pot. A side pot is created with any subsequent bets. Sometimes there can be multiple side pots. I have even seen times where there were 3 side pots (4 pots total). Side pots happen most often at the end of a tournament when there are only a few players left and the blinds are high.
Example: The blinds are 500 and 1,000. The player who is going to post the big blind has 400 in chips. Another player raises to 1,000 and the small blind calls. There is a main pot of 1,200 (400+400+400) and a side pot of 1,200 (600+600).
Sometimes it can mess things up when too many people are trying to sort out the side pots. On the other hand, it can also be helpful when the other players double-check the amount of the side pots.
HPG ADMIN on March 1, 2013