In the game of Go
), an eye is a hollow spot inside a group
of stones. Because a stone cannot be played inside a single-point eye (unless doing so would capture the group
), and a stone played inside a larger eye will, in general, end up being captured, a group with two or more eyes is unconditionally alive; that is, it can never be captured. Thus, making eyes for your groups is a crucial part of the game's tactical complexity. One must be careful for false eye
s, however. In the diagram below, the white (o) group on the left is alive with two eyes, but the white (o) group on the right is dead, because its right eye is false (black can play in the space marked "a" and capture the three stones around it, leaving the remaining group with only a single eye). Similarly, the black (x) group is alive, because of its two eyes in the middle (not to mention the fact that it can make more by capturing the right white group).