Mahjong is a four player game played by discarding and then drawing sets of tiles, similar to Rummy or some card games. During the game, players will be assigned seating (which rotates during gameplay), set the tiles in play, then draw and discard tiles in attempts to make combinations.
Similar to playing many card games, the objective in Mahjong is to create sets of tiles. Tiles can be 3 in a row, for instance a sequence "2, 3, 4." This is known as a "Chow". A "Pung" is a set of the same three tiles. A "Kong" is a set of the same 4 tiles. Each player is allowed to have as many of these sets as they can manage, but are only allowed one pair (a set of two of the same tiles), and only at the end of the game.