Mahjong, sometimes spelled Mah Jongg, is a game that originated in China, commonly played by four players (with some three-player variations found in Korea and Japan). The four player table version should not be confused with the popular Western single player (tile matching) computer game (Mahjong solitaire), which is a recent invention and completely different from the table game. Similar to the Western card game rummy, mahjong is a game of skill, strategy and calculation and involves a certain degree of chance. In Asia, mahjong is also popularly played as a gambling game (though it may just as easily be played recreationally).

The game is played with a set of 136 tiles based on Chinese characters and symbols, although some regional variations use a different number of tiles. In most variations, each player begins by receiving thirteen tiles. In turn players draw and discard tiles until they complete a legal hand using the fourteenth drawn tile to form four groups (melds) and a pair (head). There are fairly standard rules about how a piece is drawn, stolen from another player (melded), the use of basic (numbered tiles) and honours (winds and dragons), the kinds of melds, and the order of dealing and play. However there are many regional variations in the rules; in addition, the scoring system, the minimum hand necessary to win varies significantly based on the local rules being used.