A card game is a game in which the primary method of play is cards, whether traditional or game-specific. There are many card games, including families of related games (such as poker). Formally standardized rules for a small number of card games played with conventional decks have been established internationally, but most are folk games with varying regulations depending on geography, culture, and individual.
A deck or packet of playing cards has the same size and shape as a card game. Each card has two sides: the face and the back. The backs of cards in a deck are typically indistinguishable from one another.