It should be noted that there are several different sets of official rules for GO. The rules given here are similar to the American Go Association rules, and use Japanese-style scoring since that is the style used by the Internet go servers, and the style most players will likely encounter. In Section III, links will be provided (eventually) to additional pages that will discuss alternative rules. The fundamental nature of the game is the same no matter which set of rules are chosen.

2. Capturing: Two points are adjacent if they are next to each other in a vertical or horizontal but not diagonal direction. Two stones of the same colour on adjacent points are connected and belong to the same string of stones. An empty point adjacent to a string of stones is a liberty of that string. When a stone is played that reduces one or more strings of the opponent's stones to 0 liberties (in other words, when it surrounds opposing stones), those strings are captured and removed from the board.

3. Suicide: A stone may not be played if it will have 0 liberties and will not capture any of the opponent's stones. (In other words, you may not capture your own stones.)

4. Repetition: A stone may not be played if it will make the board look exactly the same as it did earlier in the game. (Repetition is not allowed.)

5. Scoring: If the last move of each player was a pass, the game ends and scoring begins. First, the players must agree on which stones on the board are dead. (Disagreements are very rare, but a rule to settle disputes will be given later.) The dead stones are considered to be captured, and are removed from the board. Each player gets one point for every opponent's stone that was captured, and one point for every empty point of territory. A group of connected empty points is territory if it is surrounded by stones of only that player's colour. The player with the higher score wins.