This might be done, for example, when the first player believes that an opponent has an inferior hand and will not call a direct bet, but that he may attempt to bluff, allowing the first player to win more money than he would by betting straightforwardly. The key point is that if no one else is keen to bet, then the most a player can raise (in a limit game) by is one single bet. If someone else bets first, he can raise, therefore increasing the value of the pot by two bets. In a no-limit game, there is no restriction to the size of one's bet and a check-raise is likely to be much larger than the second player's bet.
Of course, if no other player chooses to open, the betting will be checked around and the play will fail.
While it is an important part of poker strategy, this play is not allowed in some home games and certain small-stakes casino games. It is also frequently not allowed in the game of California lowball.
Check-raises can also be used as an intimidation technique over the course of a game. A player who has frequently been check-raised will be less likely to attempt to steal the pot.
See also
Categories: Poker gameplay and terminology