From Wikipedia (http://en.wikipedia.org/wiki/Yahtzee): "Yahtzee is a dice game made by Milton Bradley (now owned by Hasbro), which was first marketed by game entrepreneur Edwin S. Lowe in 1956. The games is a development of earlier dice games, such as "Yacht" and Generala. The object of the game is to score the most points by rolling five dice to make certain combinations. The dice can be rolled up to three times in a turn to try to make one of the thirteen possible scoring combinations. A game of Yahtzee consists of thirteen rounds during which the player chooses which scoring combination is to be used in that round. Once a combination has been used in the game, it cannot be used again.
The scoring combinations have varying point values, some of which are fixed values and others of which have the cumulative value of the dice. A Yahtzee is five-of-a-kind and holds the game's highest point value of 50 (not counting multiple "Yahtzees" in the same game)."