This is a broad genre used to described any game using playing cards as the primary device with which the game is played, be they traditional or game-specific. Countless card games exist, including families of related games (such as poker). A small number of card games played with traditional decks have formally standardized rules, but most are folk games whose rules vary by region, culture, and person. Many games that are not generally placed in the family of card games do in fact use cards for some aspect of their gameplay, but are not a primary component to the gameplay in itself. For example, UNO would be considered a card game since cards are the primary element of the gameplay.