A nine-dart finish is a perfect leg in the sport of darts, using only nine darts, the fewest possible, to check out from 501. It is notoriously difficult to achieve, even by the game's top professionals. It is considered to be the highest single-game achievement in the sport, similar to a maximum 147 break in snooker or a 300-point game in bowling.

A single game (known as a leg) of darts requires a player to score 501 points, ending with either the bullseye or a double. Each shot consists of exactly three darts and 60 is the maximum that can be scored with any one dart. Thus 180 is the maximum score of a shot, and nine throws are the minimum necessary to win.

This outshot is traditionally performed in one of three ways:

treble 20 (60), treble 19 (57) and double 12 (24)

treble 20 (60), treble 15 (45) and double 18 (36)

treble 17 (51), treble 18 (54) and double 18 (36)

Another way is to score 167 with each set of three darts, scoring a perfect 501 total, in the following way:

treble 20 (60), treble 19 (57) and bullseye (50)

The first televised nine dart finish was achieved at the MFI World Matchplay on 13 October 1984 by John Lowe, who used the third method (with the T17 first, then T18, D18) above as his outshot after scoring two maximum 180s. For this he received a prize of £102,000, and he went on to win the whole event.

More Info: en.wikipedia.org