A check-raise in poker is a strategy where a player first checks their turn to act, and then raises when an opponent bets. The goal of a check-raise is to catch an opponent off guard and to extract more value from their hand. By checking, a player can induce their opponent to bet, and then raise the bet after their opponent has shown their hand strength. This forces the opponent to re-evaluate their hand, and can often lead to them folding, thereby allowing the player to win the pot.

Check-raises are most often used in situations where a player has a strong hand and wants to extract maximum value from their opponents. They are also used as a bluffing tool, where a player with a weaker hand can try to make their opponents fold by representing strength. It is important to note that check-raises should be used strategically and not too frequently, as overuse can lead to opponents catching on to the pattern and adjusting their play accordingly. Effective use of the check-raise requires good understanding of the players at the table and the dynamics of the game.