extension

An extension is a move that extends a friendly stone or group by placing a stone at some distance from it, generally along a straight line. The distance is named by the number of vacant points between the new stone and the existing stone or group: for example, a one-space extension or a two-space extension.

Extensions give a group room to develop and help establish a base. They may also increase territorial or strategic influence while retaining the potential to connect. An extension moves away from one’s own stone or group; a jump is more commonly described as continuing a chain, without necessarily being treated as an extension from a base.

The wider the extension, the more vulnerable it may be to attack or splitting. Its safety therefore depends on nearby stones and the wider board position.