Go (baduk, Korean; wei qi, Chinese) is an ancient strategy game for 2 players who try to outwit each other by placing stones on a 19x19 board to simulate the capturing of territory. If stones of one color completely surround stones of another color, such that the surrounded stones have no liberties (adjacent open spaces), then the surrounded stones are captured by the attacker and removed from the board.

$$ How captures work: each move (1, 2, 3) captures the marked stone(s) next to it.
$$ ----------
$$ .XWW1..OB-
$$ ..XX....2-
$$ .........-
$$ ...XXXO..-
$$ ..XWWW3O.-
$$ ...XXXO..-
$$ .........-

The game ends when both players pass, seeing no advantage to playing more stones. There are variations in scoring rules, but under the common Japanese scoring system points are awarded 1 for each open space of territory that a player surrounds, and 1 for each opponent's stone captured.

Questions

Go questions regarding any aspect of the game, at any level, are welcome. For specific positional questions, diagrams are extremely useful (see below). "Why" questions, strategy questions, rules questions, joseki and joseki-deviation questions, equipment questions, bring 'em all!

To avoid confusion with the common English word, references to the game of Go should always be capitalized.

Tags

It can be useful to combine other tags with go to show what aspect a question concerns.

• Go-specific tags are: tsumego, joseki (standard opening sequences in one corner), joseki-deviation, thickness, influence, extension, leela (a Go-playing programme), kgs (online Go), 13x13, ko, seki.
• Also more or less restricted to Go: trick-move (during joseki), invasion (of opponent’s territory), shape, kifu.
• Generic tags often combined with go are: openings, end-game, counting, scoring, aesthetics.
• Less frequent generic tags: rank (in Go terms: kyu or dan), computers, computer-ai (e.g. for AlphaGo), components (for stones and boards), professional (players), handicap, etiquette, game-theory.

Diagram Markup

$$ Diagram of a ko
$$ ---------
$$ ........-
$$ ..XO....-
$$ .XC1O...-
$$ ..XO,...-
$$ ........-

This site uses the same diagram symbols as Sensei's Library. Often the easiest way to start a diagram is by copying the markup from an existing one. This can be done by clicking the "edit" button on an existing question or answer (or this wiki), and then canceling the edit.

For more details, tools and samples, see this answer to How do we enter Go Boards on this site? and the article on diagrams in Sensei’s Library, to which that answer links.

Note that Unicode includes a few handy characters, which you can cut and paste from here and use to refer to diagrams:

⓿ ❶❷❸❹❺❻❼❽❾❿ ⓫⓬⓭⓮⓯⓰⓱⓲⓳⓴
⓪  ①②③④⑤⑥⑦⑧⑨⑩ ➀➁➂➃➄➅➆➇➈➉ (second group slightly larger)
▲△ ◯⬤ note¹

Useful Links

• Sensei's Library is an excellent general resource, including terminology
• Josekipedia is a wiki for Joseki
• GoProblems.com has, predictably, Go problems.
• KGS is a popular Internet Go server.
• The article on Go in Wikipedia gives a lot of background, though less practical advice on playing.

Notes

¹ _{These are large circles, normal circles ○● look too small.}