Card solitaire (also known in Europe as "patience") is a series of card games that are generally played by a single player (similar to other "solitaire" games, such as mahjong solitaire), with the goal generally being to sort a layout of cards in a particular manner. They are generally played with one or more decks of standard playing cards (although some variations are played with specialized decks) and have many different variations. One of these variants, Klondike, became so popular that the term itself commonly refer to it.
It is a common sub-genre of video card games and is considered one of the main pillars of the "casual game" genre. One notable game is Solitaire, an adaptation of the Klondike variant that was initially added to the Microsoft Windows operating system as a tool to aid users with mouse controls, only to become one of the most played PC games of all time.