Poker is a card game in which players bet on the strength of their cards and make decisions about whether to call, raise or fold. It is believed to be an ancestor of other card games, including blackjack and rummy. A standard deck of 52 cards is used and the game can be played by two to seven players.
The game is usually played in a series of betting intervals, with the player acting last in each betting interval having an advantage over those who act earlier in their turns. After the final betting interval the hands are revealed and the player with the highest-ranking hand wins the pot.
A poker hand comprises five cards and, in the majority of poker variants, must consist of one pair or higher. The highest hand is a royal flush (ace, king, queen, jack, and ten of the same suit). The next highest hand is a straight flush; this contains five consecutive cards of the same rank (skipping one suit) or a four of a kind. Three of a kind is three cards of the same rank; two pairs contain two cards of the same rank and an unmatched card; and a single card is a singleton.
The goal of the game is to win money by making the best decisions based on available information, with the long-term expectation of maximizing profit. In order to do this, it is important to be in position at all times and not play weak hands too often.