Rummy has been one of the most famous card games for 200 years. Rummy is considered to be the most popular game in the world with over 60 global game variations and over 100 European/US variations.
The Indian version of rummy, "Indian Rummy", is a variant of 13 cards rummy games. Currently the popularity of Rummy steeply rising because of the invention of so many new online rummy variations. One can easily access the game from their phones and compete against highly skilled players from around the world. 
A Hungarian reporter coined the term rummy since the rummy card games were popular in British pubs and Irish cafes. The word rummy is a British slang used to describe a drunkard or a ruffian. The game was fairly popular in European countries during the First World War. The soldiers would regularly play these games in the camps and the cafes.
Rummy can be traced back to the early 19th century. The Spanish immigrants brought a variation of this game to America. 
Conquian card game from Spain and Mexico is thought to be a predecessor of rummy.
Another origin story states that Mahjong, a popular Chinese game, was the progenitor of the modern rummy game. The theory suggests that the Chinese created the card game as it was inconvenient for them to carry the mahjong tiles with them. The Chinese version later trickled down to the Indian sub-continent and became famous here. The Indian rummy game is also known as Paplu.
Gin rummy and 500 rummy are the most popular rummy games in the USA.
In 1970, the movie Poker showed a game of rummy as it was popular in most American households.
For the last 51 years, rummy, Poker and Sports Betting are considered to be the highest level of residential gambling.
Between 1960 and 1970, rummy, as a social game, was played more times than all the other board games combined. 
Rummy is also known as the mother of all card games as it is known to give birth to card games like Pinochle and Bridge. 
The instructions of rummy are so simple that new players only need 15 minutes to understand the rules and start their first game.


reference: https://www.a23.com/rummynews/cms/blog/17-interesting-facts-about-rummy-that-every-player-should-know-about/