Quite simply the sport's Holy Grail, the nine-dart finish represents perfection in darts.
The darting equivalent to a 147 in snooker or a perfect game in bowling, a nine-darter is also referred to as a perfect leg, with zero margin for error to be achieved.
A nine-dart finish, also known as a nine-darter, is when a player takes nine darts to finish a leg of 501, and is the fewest darts that can be thrown to win a leg.
Requiring nine perfect darts, a nine-darter typically requires two scores of 180 followed by a finish of 141, though variations of the method are occasionally seen.
Sometimes players will score 180, 177 and require a 144 finish, whereas in the Grand Prix, where legs can't be started until a player has hit a double, usually requires a finish on the bullseye.
Brendan Dolan hit the first nine-darter in the Grand Prix, starting with D20, T20, T20 for a score of 160. After a 180, a score of 161 was left, with Dolan checking out on the bull.