12) Counting: There are two methods for counting the score at the end of the game. One is based on territory, the other on area. The players should agree in advance of play which method they will use. If there is no agreement, territory counting shall be used.

(Although players' scores may differ under the two methods, the difference in their scores, and hence the game result, will be the same.)

Territory: Those empty points on the board which are entirely surrounded by live stones of a single color are considered the territory of the player of that color.

(At the end of the game, the empty points remaining on the board fall into regions. A region is the smallest set of empty points containing a given empty point and any empty points adjacent to any empty point in the set. That is, a region consists of those empty points which can be reached from a given empty point by moving only to adjacent empty points. A region is entirely surrounded by stones of a single color if the only stones adjacent to empty points in the region are of that color. There are situations (Japanese seki) in which a region of empty points is left at the end of the game which is not entirely surrounded by stones of a single color, and which neither player would fill because to do so would bring dire consequences. See Figure 4. When counting by territory, it is also possible that there will be some neutral points left between live groups belonging to the two players which have not been filled, although it is customary to fill all such points before scoring the game.)

Figure 4.