capping move

A capping move—also called a capping play or boshi—is played above an opposing stone or group, usually with some space between the stones. The cap is placed on the outer side above the target, while its exact distance and direction depend on the surrounding position.

Its purpose is to prevent or discourage an extension, reduce the opponent’s room to develop, and build influence or attacking potential. Unlike a pincer, which approaches from the side, a cap is defined by being played above the opposing stone or group. A cap is a positional attacking move, not automatically a forcing move: its value depends on the surrounding stones and on the escape options available to the opponent.