The game itself consists of thirteen rounds; in each round, the five dice are rolled (with two re-rolls of any subset of the five permitted). After the dice have been rolled thus, they must be sorted into one of the thirteen scoring categories:
- Sum of 1's, 2's, and so on (the so-called "upper section;" you get a bonus if you score at least 63 points overall in this section)
- Three-of-a-kind, four-of-a-kind, full house, run of four, run of five, five-of-a-kind (also called the "Yahtzee," also the most valuable category at 50 points), and "chance" (sum of the numbers displayed).
Each "box" can only be scored once, so if you don't get anything good, you pick one of the categories and score zero for it (which sucks if you get that thing next round).
The goal is to maximize score. Are you a bad enough dude to get a perfect 375?
Don't confuse it with that guy who does Zero Punctuation.
Official Instructions from Hasbro's website.
An optimal strategy for playing Yahtzee with computer assistance.