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.

A game is a structured type of play, usually undertaken for entertainment or fun, and sometimes used as an educational tool. Many games are also considered to be work or art.