One place to play Canasta online is www.games.com/canasta-games. The site offers multiple versions of the game, including classic Canasta, Canasta for Two and Canasta Lite. Other ways to play Canasta online include PlayOK and Club Pogo.
PlayOK has a free sign-up, or you can play Canasta online as a guest. Once you log in, you can create a new table or join a game that needs players. Club Pogo offers a one-week free trial and costs $6.99 per month thereafter, as of July 2015. Once you sign up, you can play Canasta against other Club Pogo users or against the computer at any time.
According to The Games Journal, Canasta is a card game that combines elements of bridge, rummy and a rummy variant called "cooncan." The game is most commonly played by four players on two teams, using two decks of cards. The game was created in 1939 in Uruguay by Segundo Santos and Alberto Serrato, two professionals who often played cards together at Montevideo's elite Jockey Club. The game spread to other Latin American countries throughout the 1940s before arriving in the United States during the 1950s, where it experienced a surge of popularity.