- Go is played on a 19x19 square grid of points by two players called black and white.
- Each point on the grid may be either colored black, white or empty. A point P is said to contact a color C, if there is a path of orthogonally adjacent points of P's color from P to a point of color C.
- Starting with an empty grid, the players have alternate turns, black first.
- A turn is either a pass; or a move that does not generate a grid pattern identical to one that this player has generated previously.
- A move consists of coloring an empty point with the player's color, then recolor all the opponent-colored points to empty which don't contact empty (called capture of opponent stones), and then recolor all the player's own-colored points which don't contact empty (called remove suicide stones).
- The game is finished after two consecutive passes.
- A player's score is the number of points of his color, plus the number of empty points that don't contact the opponent's color. Maybe for the advantage of beginning the game the other player gets a fixed number of points (called Komi).
- The winner is the player with the greater score at the end of the game; if the scores are equal it is a draw.

- The grid of points is usually marked by a set of 19x19 lines on a wooden board. Each player has an arbitrarily large set of stones of his own color. By prior agreement a rectangle of different dimensions may be used.
- For handicap games, by mutual agreement, the weaker player may be awarded a handicap of "n stones"; which means he is black and begins with n consecutive turns before white's first. Note that a 1-stone handicap is thus the standard game; this is a considerable advantage to black, and to get a more even game between equals it is usual to add an extra 7 points to white's score at the end of the game. This 7 points is called the "komi".
- "Has left previously" means by either a move or a pass.
- Using boards, coloring an empty point means placing a stone of one's own color on the point, (a line intersection of the board). Coloring a point empty, i.e. emptying a point, means removing the stone from it.
- A player who says "pass", must be interpreted as saying: "I hereby formally pass if you make another move; and also if you say pass and we can agree to remove the obvious dead stones still on the board before counting the scores; but if we disagree on these it is still your turn." Then if both players say "pass", but disagree on removal, the second speaker's concession of turn (being later) over-rides the first, and the first speaker moves again. It should then be a matter of propriety that any subsequent saying of "pass" should be phrased "I formally pass", and be accepted as binding as in rules 6 and 7.
- The scores can be conveniently counted (after removal as in interpretation 6 has occurred), by counting up each player's points on the board as it then stands. [NOTE: There is an alternative method involving putting removed stones back on the board and re-arranging all the stones; but this is not recommended for learners.]

Grateful acknowledgement to John Tromp for most of the ideas here, and for many helpful comments and conversations on these matters.

Bill Taylor