Rummy is a standard deck playing card game using 52 cards. It is one of the most popular family card games, and has a simple premise. Players are dealt a hand of cards, with the goal being to rid yourself of all the cards in your hand. You can do this by playing cards to the table, in groups of three, either in sets (groups of cards with the game value from different suits) or in runs (three or more consecutive cards for one suit). Once a person lays down a group of cards, other players -- including the player who played the original set -- can now "lay off" cards to that group.
On a player's turn, they can take the top face down card from the stock, or take the top face up card from the discard pile. After melding, laying off, or making no plays on the table, a player must discard a card face up on the discard pile. (Variant: The discard pile is spread out, so that the value of all cards is visible. If you see a card that you can use, you may take it, but you must also take all the cards that have been discarded on top of it, and you must play the lowest (physical) card in the deck as soon as you pick it up.)
The hand ends as soon as one player gets rid of all his cards (going out). All players add up the pip values of the cards in their hands (Face cards are ten points apiece), and those points are given to the player who went out. A player who goes out without previously laying down any cards goes "rummy," and scores double the points. (Variant: Cards on the table are worth positive points, and cards left in your hand are worth negative points. Numbered cards from 2-9 are worth 5 points apiece; 10s and face-cards are worth 10 points apiece; and aces are worth 15 points apiece.) Normally, games are played to 500 points, but players can opt to play to fewer points, or play a specific number of rounds.
When playing with 2, both players get 10 cards. When playing with 3 or 4, each player gets 7 cards. When playing with 5 or 6 players, each player receives 6 cards.
This is the most basic version of Rummy. There are many other variations of the game.
Online play: