Capture & atari
1. See it. Tap the white stones — the group is connected and down to one liberty. One liberty = atari.
The one rule of Go: when a stone or a connected group has no liberties left, it is captured and lifted off the board.
Atari is the warning state — exactly one liberty remaining, one move from capture. Connected stones share their liberties as a single unit, which is why you connect: a group is harder to surround than lone stones.
- Adjacent same-colour stones form one group with shared liberties.
- You can never play a stone that would have no liberties (suicide) — unless it captures something first.
2. Do it. Black to move — play the last liberty at the marked point to capture both white stones.
Place the black stone on white's final liberty. The instant white reaches zero liberties, both stones vanish and the board reports the capture.
Captured stones are worth a point each at the end — capturing is one of the two ways you score. The other is territory, which is the final lesson.
Try an illegal move too: placing black where it would have no liberties (and captures nothing) is rejected as self-capture.