Relatively speaking, Canasta is a newer card game.  Since most popular card games can actually be traced back a few hundred years and have been played throughout several countries, Canasta seems quite young in comparison as it was invented in only 1939.  That being said, Canasta shot up in popularity extremely quickly from that point, joining among the much older games in its popularity in many of the card playing nations of the world.  In fact, it has become so popular that there have already been a number of variations of the game that have developed.

it might seem confusing since it is a newer game but this might help:
http://www.pagat.com/rummy/canasta.html