Life and Death

An eye is a single empty point surrounded by one player. Unless a move there captures some stones, the opponent can't play in an eye due to the suicide rule.

A single eye can be completely surrounded and captured:

When a group has two eyes, it is safe from capture, even if completely surrounded, as the opponent can't play in either eye. Such a group is alive. For example:

Beware of false eyes where the stones surrounding your eye can be captured: it is important to keep the stones around your eye connected by controlling the diagonals. For example, the following groups have a false eye due to the stones marked with triangles:

Stones that can not make two eyes and that can be captured no matter what are often left on the board at the end of the game and just counted for the opponent. For example, the two black stones are dead and will be counted for White at the end of the game:

With the AGA rules used by SmartGo, the score remains the same whether White captures these stones or not.

Seki

Blocks can be alive in seki when they coexist in such a way that neither player wants to play. For example:

A move by either player would let the opponent capture, so both blocks stay on the board and are counted as alive at the end of the game.