Go

Overview

Two players alternately place stones on the intersections of a grid, claiming territory by surrounding it. The rules fit on a postcard. The game does not.

How far this page is checked. Go has no single rulebook: Japanese, Chinese, Korean and American rule sets all exist and differ at the edges. The core rules below (liberties, capture, suicide, ko, passing and the end of the game) are checked against the American Go Association's concise rules, as the British Go Association publishes them for its tournaments. That text dates from 1991, so figures that have changed since, notably komi, and the handicap and rank tables, are not checked and vary by rule set.

1. Board and equipment

Standard play uses a 19×19 grid — 361 intersections. Smaller boards are normal for teaching and quick games:

Board	Use
19×19	Standard, tournament
13×13	Intermediate, faster
9×9	Teaching, tactics practice

Nine marked points, the star points or hoshi, guide handicap placement.

Black plays first. Stones go on the intersections, not inside the squares, and once placed they never move.

There are 181 black stones and 180 white — exactly enough to fill the board.

2. Liberties and capture

An empty intersection orthogonally adjacent to a stone is a liberty. Diagonals do not count.

Stones of the same colour that are orthogonally adjacent form a group and share all their liberties. A group lives or dies as a unit.

When a placement removes a group's last liberty, that entire group is captured and lifted from the board immediately.

Capture is resolved before anything else. This matters for the suicide rule below.

3. Illegal moves

Suicide

You may not place a stone that leaves its own group with no liberties.

Unless that same placement captures an enemy group first — removing those stones creates a liberty, and the move becomes legal.

Ko

You may not play a move that recreates the exact board position immediately after your opponent's previous move.

Without this rule, a single stone could be captured and recaptured forever. The practical consequence is that you must play elsewhere first — a ko threat — large enough that your opponent answers it rather than resolving the ko. The position then differs, and you may retake.

Superko, used in Chinese and American rules, forbids recreating any previous whole-board position, not just the immediately preceding one. The AGA wording: "It is illegal to play in such a way as to exactly recreate a previous full board position from the game, with the same player to move."

4. Life and death

A group is alive if it cannot be captured no matter how the opponent plays. A group is dead if it cannot avoid capture.

The key concept is eyes — enclosed empty points surrounded by one group.

• A group with two separate eyes is unconditionally alive. The opponent cannot fill both, because filling the first would be suicide.
• A group with one eye, or one large eye that can be reduced to one, can be killed.

Seki is a mutual-life stalemate: two adjacent groups each lack two eyes, but neither can capture the other without self-destructing. Both live, and the shared liberties score nothing.

Dead stones are not removed during play. They are agreed and removed at the end. Playing out a dead group to prove it is considered poor form among strong players and costs points under Japanese rules.

5. Ending the game

Either player may pass instead of placing a stone. Two consecutive passes end the game.

Players then agree which groups are dead. Dead stones are removed and count as prisoners.

If they cannot agree, play resumes to settle it. Under the AGA rules the opponent of the last player to pass moves first. If agreement still fails and both players pass twice in a row, every stone left on the board counts as alive.

The AGA rules also use pass stones: a player who passes hands the opponent a stone as a prisoner, and White must make the last move. That makes territory and area counting give exactly the same result.

6. Scoring

Two systems are in common use. They almost always produce the same winner, and usually differ by no more than a point.

Japanese — territory scoring

Empty intersections you surround, plus prisoners you captured.

Under this system, playing an unnecessary stone inside your own territory costs you a point, so players stop as soon as the boundaries are settled.

Chinese — area scoring

Empty intersections you surround, plus your own stones on the board.

Prisoners are irrelevant. Playing an extra stone in your own territory is neutral, which makes this system more forgiving for beginners and easier for computers.

7. Komi and handicap

Komi compensates White for moving second. The amount depends on the rule set and has risen over the years; the 1991 AGA text says 5½, and most current events use more. Always check the event's figure. The half point makes draws impossible.

Handicap lets players of different strength compete. The weaker player takes Black and places stones on the star points before White's first move:

A rough guide, not part of any rule set checked here:

Handicap stones	Approximate rank difference
2	1 rank
4	3 ranks
9	8 ranks

Komi is reduced to 0.5 or eliminated in handicap games.

8. Ranks

Level	Range	Direction
Kyu (student)	30k to 1k	Lower is stronger
Dan (master)	1d to 7d amateur	Higher is stronger
Professional dan	1p to 9p	Higher is stronger

A one-rank difference is roughly one handicap stone. A complete beginner is around 25–30 kyu.

9. Basic principles

Not rules, but the conventions every teacher starts with:

• Corners first, then sides, then the centre. Corners need fewest stones to enclose territory.
• Do not play close to strength — your own or your opponent's.
• A group with two eyes is safe. Most tactical fights are about making or denying the second eye.
• Sente and gote. A move your opponent must answer keeps initiative (sente); one they can ignore surrenders it (gote).

Commonly argued

• Diagonals are not connections. Two stones touching only at a corner are separate groups, though they are usually hard to cut apart.
• Suicide is illegal, except when it captures first. The capture resolves before your own group's liberties are counted.
• Ko applies to the immediately preceding position only under Japanese rules. Chinese superko is stricter.
• Dead stones are not captured during play. They are agreed at the end. You do not need to play them out.
• Filling your own territory costs a point under Japanese scoring but not Chinese — which is why the same game can be scored differently.
• There is no draw when komi has a half point.