Canasta is a card game with melding that originated in South America in the early 20th century. It is played with two decks of cards and four players, with each player being dealt 15 cards. The goal of the game is to form melds, which are sets of three or more cards of the same rank, and then lay them down on the table. Players can also add cards to existing melds on the table. The first player to reach a predetermined number of points wins the game.