Jigo ジゴ（持碁）is the Japanese Go term for the condition at the end of the game when both Black and White have equal number of points. Before the introduction of fractional values for komi, this condition often led to a drawn game (with neither side winning), and is counted as such in the results.
For tiebreak purposes, some tournaments assign a win to a player when a jigo occurs. For example, in the old Meijin (komi was 5.0), it is counted as a win for White. Similariy, Ing's rules stated a komi of 8 points but considers Black the winner in the case of a jigo.
The term "no result" should be distinguished from jigo: when a "no result" occurs, the game is treated as if it was never played.
"JiGo" is also the name of a suite of Go-tools being developed at http://www.whitemagicsoftware.com/software/java/jigo/.
The korean term 빅 (bik) is also used for a seki. The other term, 화국 (hwaguk), means "game of peace".
It is a little tricky in the way the words are carried over into English (and other western languages) from Japanese. In Japanese 'Jigo' means exactly the situation where both players have the same number of points. The game result is hikiwake, meaning a draw. The result of triple ko and other special repeating positions where the neither side will give up the repetition is mushoubu, meaning "no result".
In professional games jigo results in a true draw and is counted in the results, for example, of the ten-game matches (jubango) that Go Seigen played against all his top rivals in the 1940's and 1950's. On the other hand, mushoubu requires a replay of the game. In the 1980 Meijin tournament between Cho Chikun and Otake Hideo there was a mushoubu. If the series had gone the distance, the players would have ended up playing eight games to finish a seven-game match. -- Dave Sigaty
JF There is a very good reason for not misusing the term jigo to mean draw. It is not always a draw. In the old Meijin and some other tournaments jigo was a valid result on the board (komi was 5.0) but in the tournament it counted as a win for White.
Charles And, as John knows too, the jigo win was for tiebreak purposes less than a win: with an unexpected impact on the First Meijin League.
Andrew Grant: Of course, saying "5 points komi, White wins jigo" is functionally equivalent to saying "5.5 points komi" - it's a distinction without a difference, really. I've never understood why people insist on the "White wins jigo" wording.
Anonymous: Because it's horrible! Half a point? What _is_ that? The score is a whole number. Why not have a komi of seventeen-thirds or two times the base of the natural logarithm. Five and a half is simple and it works, but it's rather bizarre at the same time.
Gregory: Baseball has "tie goes to the runner", so I hear nothing unusual in "tie goes to white" or "tie goes to black" depending on the whole number of komi. I agree that the fractional komi is very distasteful to the sensibilities, even if useful for calculations. Anon: come on people... in 98% of all games the half point means nothing. if you don't like it, ignore it until you need it to decide who wins.
Anonymous: The first 5 points of the komi serves a completely different purpose than the remaing 0.5. If 5 point komi is the komi most likely to result in a jigo between equal players, then you could question why jigo should count as a white win. And if you ask that question, you might end up playing with a 4.5 komi instead to favor black. So, there is some sense in explicitly specifying that the 5 points are compensation for not starting, and "white wins jigo" is the tiebreaker rule.