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Komi is a Japanese term from the game of Go (aka Wei Qi/Badouk). It is provable that ordinarily, the person playing black (Black plays first in Go) has an advantage, in that perfect play from both sides must either result in a draw, or a win for Black. White must therefore be given some sort of advantage to compensate. Komi is a fixed number of points granted to White (or subtracted from Black - there's no difference) to compensate for Black's first move advantage. The number of komi points can vary from country to country and organization to organization, but most rulesets use a komi of 5.5 or 6.5, as those komi are generally believed to give equal players approximately equal chances of winning. The fractional komi serves the double purpose of also preventing a tie (except in exceptional circumstances like superko).

Komi can also be used to compensate for a difference in skill between two players. The weaker player can be given the black stones, and White's komi can be reduced, or even made negative. This is only a good method of compensating for skill differences if the difference is small. See the Handicap Stone node for a more common method of dealing with larger differences in skill.