One way to make territory is to "capture" opponent's stones.
Stones that are surrounded are removed from the board and are handed to the
opponent as prisoners.
Each prisoner will be worth one point.
With one more move, the white stone will be completely surrounded and will be removed.
Stones that can be removed with one more move are said to be in "Atari".
The white stone is now surrounded. Therefore...
... it is removed from the board.
If it were white's
turn, it could "escape" by connecting another stone.
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