Mus is a card game widely played in Spain, France and Hispanic America. Originating in the Basque Country, it is a vying game. The first reference to this game dates back to 1745, when Manuel Larramendi, philologist and Jesuit Basque, quoted it in a trilingual dictionary (Basque-Spanish-Latin).

A card game is any game that uses playing cards as the primary device with which the game is played, whether the cards are of a traditional design or specifically created for the game (proprietary). Countless card games exist, including families of related games. A small number of card games played with traditional decks have formally standardized rules with international tournaments being held, but most are folk games whose rules may vary by region, culture, location or from circle to circle.