Joseki (j?seki) are established sequences of play which (locally speaking) are considered to give an optimal result to both players. There are thousands of such lines that have been researched and documented.

Often joseki are played out early in the game and involve dividing the corners. There are also "mid-game joseki", dealing with for example an invasion into a common enclosure or framework.

Though joseki have some parallel with chess openings, they differ significantly. Chess openings structure the whole board while joseki deal only with a local position. Therefore the choice of which joseki (of many possible) to play in any given situation should be based on an assessment of the global position. This includes considerations of the direction of play, current balance of territory and influence, and one's own game strategy.

It is also quite possible to deviate from joseki and obtain a good result if the surrounding position allows. In other words, joseki are sensitive to the context in which they are played.

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