Contract bridge, or simply bridge, is a trick-taking card game using a standard 52-card deck. In its basic format, it is played by four players in two competing partnerships, with partners sitting opposite each other around a table. Millions of people play bridge worldwide in clubs, tournaments, online and with friends at home, making it one of the world's most popular card games, particularly among seniors. The World Bridge Federation (WBF) is the governing body for international competitive bridge, with numerous other bodies governing it at the regional level.

The game consists of a number of deals, each progressing through four phases. The cards are dealt to the players; then the players call (or bid) in an auction seeking to take the contract, specifying how many tricks the partnership receiving the contract (the declaring side) needs to take to receive points for the deal. During the auction, partners use their bids to also exchange information about their hands, including overall strength and distribution of the suits; no other means of conveying or implying any information is permitted. The cards are then played, the declaring side trying to fulfill the contract, and the defenders trying to stop the declaring side from achieving its goal. The deal is scored based on the number of tricks taken, the contract, and various other factors which depend to some extent on the variation of the game being played.

Rubber bridge is the most popular variation for casual play, but most club and tournament play involves some variant of duplicate bridge, where the cards are not re-dealt on each occasion, but the same deal is played by two or more sets of players (or "tables") to enable comparative scoring.