Figure 2.White 1 captures the Black stones

}

6) Repeated Board Position (Ko): It is illegal to play in such a way as to recreate a previous board position from the game, with the same player to play.

{The most typical example is a situation where the players can each alternately capture and recapture a single stone. This is known as "ko" (See Figure 3). After the first capture, the player moving next may not capture immediately, as this would repeat the board position; instead, that player must play elsewhere on the board (or pass). The player who first captured may then "fill" the ko (or otherwise resolve it), or play elsewhere as well (often in response to the other player's previous move.) If the board position has changed, and the ko has not yet been resolved, the opponent is then free to capture, and it is the original player who may not then immediately recapture. This process is known as a ko fight, and the moves played away from the ko itself are known as ko threats.

Figure 3. Ko

Rarely, multiple kos or other repetitive situations will arise; the principle for handling them is always the same: the players must avoid repeating the full-board position, so they are periodically, and alternately, forced to play away from the repetitive situation before responding.}

7) Passing: On his or her turn, a player may pass by handing the opponent a stone, referred to as a pass stone, rather than playing a stone on the board.