Go has no piece values and no material count. What it has instead is liberties, and almost every tactical question reduces to who runs out of them first.
Counting a group's liberties
Take every stone in the group and count the empty points adjacent to any of them, without double-counting. A long snaking group can have many liberties; a compact square of four stones on the edge has surprisingly few. Shape matters more than stone count.
This is why beginners lose groups they thought were solid: four stones in a tight block have eight liberties, while four stones in a line have ten. Compact is strong for eye space and weak for breathing room.
Atari and the wrong response
Atari means one liberty left. The instinctive reply is to extend — add a stone to gain more liberties. That is often right, but three questions come first.
- Is the group worth saving? Two stones in the corner may be worth less than a move elsewhere.
- Can I capture something instead? Capturing in reply often gains more liberties than extending.
- Will extending just walk into another atari? Running along the edge with two liberties is a slow way to lose more stones.
The capturing race
When two adjacent groups are both short of liberties, only one can survive. This is a semeai, and the arithmetic is straightforward: count your liberties, count theirs, and note whose turn it is.
If you have more liberties, fill theirs and win. If you have equal liberties and it is your turn, you win. If you have fewer, do not start the fight — play elsewhere and take the points.
Shared liberties change the count
Points adjacent to both groups belong to both counts, and they are the last to be filled, because filling one puts your own group in atari too. The practical rule: shared liberties favour whoever has more outside liberties. Count outside liberties first, then add shared ones to the total for the side that will fill them last.
Snapback and the stone you should not capture
A snapback is a sacrifice: you offer one stone, the opponent captures it, and the resulting shape puts their whole group in atari so you capture it all back. It happens whenever capturing would fill your opponent's own last liberty.
The lesson is defensive as much as offensive — before you capture a lone stone, check whether taking it leaves your group with one liberty.
Practical habits
- Count liberties before every fight, not during it.
- Extend toward open space, never toward the edge, when escaping.
- A group with four or more liberties is rarely in immediate danger; two or fewer is an emergency.
- If a capturing race is lost by one liberty, look for an outside move that adds one — a placement that reduces their count works just as well.