Poker is a card game in which players wager against each other based on the strength of their hand. There are countless variations of the game, but they all share certain essential characteristics. Each player is required to place a forced bet (the ante or blind) before the cards are dealt, and then the players’ hands develop through one or more rounds of betting. The player with the highest ranked hand wins the pot.

In addition to the forced bets, a player may choose to put additional money into the pot for strategic reasons. For example, a player may raise (put in more money) when they think their hand has positive expected value or when they are trying to bluff other players. Generally speaking, a player’s decisions are made on the basis of probability, psychology and game theory.

For example, suppose you hold a pair of kings on the deal but an ace on the flop means your pocket kings aren’t as strong as they used to be. In this case it’s usually best to call.