In most darts tournaments, players compete in matches comprising shorts games, or "legs". The object of each leg is for a player to reduce his score from 501 to zero as quickly as possible.

In the PDC World Darts Championship, sets are the best of five legs, meaning a player needs to win three legs to win the set. However, there is a special rule if the match goes to a deciding set ...

The minimum number of darts required to checkout is nine. An example of a "nine-darter" would be a player throwing two 180s, then a checkout of 141 (treble 20, treble 19, double 12).