From the publisher's website:

The classic game is for four players in two partnerships. Variations exist for two and three player games wherein each plays alone, and also for a six player game in two partnerships of three. If partners are chosen they must sit opposite each other. Canasta uses two complete decks of 52 playing cards (French Deck) plus the four Jokers. All the Jokers and twos are wild cards. The initial dealer is chosen by any common method, although it should be remembered that in Canasta there is no privilege or advantage to being the dealer. Rather the true privilege is of first play and access by that player to any chance bonus card which might have been turned up, and subsequently covered, at the conclusion of the deal (e.g., if a red three or wild card had been turned up at the end of the deal, it must and would have been covered by a legitimate play card which itself could then be used by that first player in making the initial meld and taking the discard pile and thus giving that first player those bonus cards). The deal then rotates clockwise after every hand. The dealer shuffles the pack, the player to the dealer's right cuts, and the dealer deals out 11 cards to each player. The remaining cards are left in a stock in the center of the table. The top card from the stock is turned over to form the discard pile. If this first turned card is a red or black three, or a wild card, additional cards from the stock are turned over to the top of the discard pile until the top card of the discard pile is neither a three nor a wild card. If one of these bonus cards was a wild card, it freezes the discard pile until that discard pile containing the wild card has been legitimately taken into a player's hand. A bonus red three taken in this manner is not replaced by another card from the stock, as it would if it had been drawn from the stock during a player's regular turn. Any player who receives a red three in their initial hand must immediately play it to the table team and draw a new card from the stock to their hand.