Go (game)
The playing pieces are called "stones". One player uses the white stones and the other, black. The players take turns placing the stones on the vacant intersections ("points") of a board. Once placed on the board, stones may not be moved, but stones are removed from the board if "captured". Capture happens when a stone or group of stones is surrounded by opposing stones on all orthogonally-adjacent points. The game proceeds until neither player wishes to make another move. When a game concludes, the winner is determined by counting each player's surrounded territory along with captured stones and komi (points added to the score of the player with the white stones as compensation for playing second). Games may also be terminated by resignation. A teacher might simplify the explanation by saying to a student "you may place your stone on any point on the board, but if I surround that stone, I will remove it."
Dunhuang Go Manual
The fourth section (像名弟四) discusses the symbolism of the Go board and the symbolic names given to different positions on the board. For example, the author states that "Go stones are round in imitation of the heavens, and the Go board is square in the same way that the earth is; that there are 361 intersections on the board reflects the division of the ecliptic [into 365 days]" (碁子圓以法天，碁局方以類地。碁有三百六十一道，倣周天之道數). The explicit mention here that a Go board has 361 points indicates that the author of the manual was familiar with the standard board with a 19 × 19 grid, and not the earlier 17 × 17 grid board that is attested in archaeological evidence dating back to the late Han Dynasty (206 BCE – 220 CE) and from paintings dating up to the mid 8th century.