With a history spanning several centuries, rummy is a popular card game. Its roots can be found in the United States of the 19th century, and the Chinese tile game Mahjong may have had some iteen patti livenfluence. Europe and Asia were soon affected by the game's rapid global expansion in popularity. Rummy has taken on many different forms over time, each reflecting changes in culture. Gin Rummy first appeared in the United States in the early 20th century, and with it the idea of "knocking," in which players can end a game by laying down their entire hand at once, was introduced.