Go (game)
Two players, "Black" and "White", take turns placing a "stone" (game piece) of their own color on a vacant "point" (intersection) of the grid on a Go board. Black plays first. If there is a large difference in skill between the players, the weaker player typically uses Black and is allowed to place two or more stones on the board to compensate for the difference (see Go handicaps). The official grid comprises 19×19 lines, though the rules can be applied to any grid size. 13×13 and 9×9 boards are popular choices to teach beginners, or for playing quick games. Once placed, a stone may not be moved to a different point.
Go equipment
One specific type of plastic stone is called the Ing stone, manufactured by the Ing Chang-ki Wei-chi Education Foundation. These are the official stones of the Ing Foundation and have some extra weight to them due to metal inserted in the middle of the stone. They are 10 mm thick and sometimes come in an Ing Bowl, which is specially designed to count them (Ing rules require each player to start with exactly 180 stones).