Capturing
Everything in Go comes down to liberties. A group dies when you take its last one — so the whole game is the fight over where those liberties are.
Atari: one liberty left
When a group is down to its last liberty, it is said to be in atari. That single point is the only thing keeping it alive — take it and the whole group comes off the board.
In atari
The white group has one liberty left. Fill it and three stones are captured at once.
Reading ahead
- Always check whether a group you are about to fill is in atari — capturing is worth more than a single stone's worth of territory.
- A group with two eyes (two separate one-point spaces it can never be filled) can never be captured. Learn to make two eyes and your stones are safe.
- Connected stones share liberties. Splitting the opponent is one of the strongest moves in the game.
Ladders
A ladder is a chase: you atari a stone, the opponent runs, you atari again, and so on. The chase always travels in a straight line — and always toward the edge. A ladder only works if you can keep the stones in on the side you are driving them.
The chase
You chase; the opponent runs. Near the edge there is nowhere left to run, and the stone is captured.
If a stone the opponent can atari is itself in atari when you move, the ladder fails and nothing is captured. Ladders are a short-range tactic; on an open 19×19 board they almost never work.