Poker is a popular type of card game in which players bet on the value of the card combination ("hand") in their possession, by placing a bet into a central pot. The winner is the one who holds the hand with the highest value according to an established hand rankings hierarchy, or otherwise the player who remains "in the hand" after all others have folded (the player who makes an un-called bet.).

Poker has many variations, all following a similar pattern of play. Depending on the variant, hands may be formed using cards, which are concealed from others, or from a combination of concealed cards and community cards.

Other games that use poker hand rankings may likewise be referred to as "poker". Video poker is a single-player computer game that functions much like a slot machine.