The rummy is member of the very large classification of games known as
draw and discard games. The object of these games is to improve one's hand by forming it into sets of matching cards (either same
rank or sequence in a
suit). The basic move is to
draw one (or more cards) from an undealt
deck or from the
discard pile, possibly
meld a set or sets, and
discard a card. Historically, these games appear to be
Chinese origin. Although they are now widespread, they were unknown outside the
orient until the 20
th century.
The basic rummy game is to simply form your entire hand into sets as soon as possible. Whenever someone succeeds in this and goes out, players loose a fixed amount, or may be penalized according to the number of unmelded cards they have left.
There exist also knock rummy games. In these games, it is not necessary to have all of your cards in sets before going out. Instead, you may knock when you think that the value of the unmatched cards (deadwood) is less than that of the other players. If you are right, you win, but if any other player can do better, you are very penalized.