As new games are invented all the time, the number of card games in existence is unknown. Besides strictly card-based games, a number of other types of games involve the use of cards, making the number even more difficult to estimate.
Traditional card games involve the use of a standard deck of playing cards. These include games like blackjack, spades and gin rummy. Another type, referred to as a "trading card game" or "collectible card game," uses specially designed cards that often contain drawings of mythological creatures. Some games, like solitaire, are played by a single person, while others require multiple players or teams.