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 tactics
As explained in the section on important consequences of the basic rules, some formations of stones can never be captured and are said to be "alive", while other stones may be in the position where they cannot avoid being captured and are said to be "dead". Much of the practice material available to students of the game comes in the form of life and death problems, also known as "tsumego". In such problems, players are challenged to find the vital move sequence that will kill a group of the opponent or save a group of their own. "Tsumego" are considered an excellent way to train a player's ability at reading ahead, and are available for all skill levels, some posing a challenge even to top players.