The Ancient Game of Go

Go is an adversarial game with the objective of surrounding more territory than one’s opponent.  As the game progresses, the board gets divided up into areas of territory, as outlined by groups of stones. These areas are then contested in local battles, which are often complicated, and may result in the expansion, reduction, or wholesale capture and loss of the contested area. It is often the case that a certain kind of “trade” goes on, where a player’s loss in one part of the board can be compensated for or mitigated by a gain in another part of the board.
A basic principle of Go is that stones must have at least one “liberty” (Chinese: 氣) to remain on the board. “A liberty” is an open “point” (intersection) next to a stone. An enclosed liberty (or liberties) is called an “eye” (眼), and a group of stones with at least two separate eyes is said to be unconditionally “alive”. Such groups cannot be captured, even if surrounded. “Dead” stones are stones that are surrounded and in groups with poor shape (one or no eyes), and thus cannot resist eventual capture.
The general strategy of Go is to expand one’s territory where possible, attack the opponent’s weak groups (groups that can possibly be killed), and always stay mindful of the “life status” of one’s own groups. The liberties of groups are countable. Situations where two opposing groups must capture the other to live are called capturing races (‘semeai’ in Japanese). In a capturing race, the group with more liberties (and/or better “shape”) will ultimately be able to capture the opponent’s stones. Capturing races and questions of life and death are examples of what makes go challenging.
The game ends when both players pass, and players pass when there are no more profitable moves to be made. The game is then scored: The player with the greater number of controlled (surrounded) points, factoring in the number of captured stones, wins the game. Games may also be won by resignation, for example if a player has lost a large group of stones.

The Game Stages and Moves

Aji — Aji in Go refers to lingering possibilities that are latent and cannot be used immediately, but might come to life if the situation changes..  It can be a weakness that is left behind in the opponent’s position. Typically it can be exploited in more than one way.
Damezumari — Inability to play at a tactically desirable point due to lack of liberties.
Endgame — The final stage of the game.
Fuseki — Arraying forces for battle; it refers to the initial phase of the game, especially before there are any weak groups.
Gote — A move or sequence of moves that does not have to be, or is not, answered.
Honte — A solid move.
Influence or eikyō suru– The effect stones exert at a distance.
Joseki — Established sequences of play considered equitable for both players, especially early moves near a corner.
Kikashi — A forcing move for a sente move that produces a certain effect and can then be abandoned without regret.  Kikashi is a move that produces a whole-board, and subtle positive effect in preparation of future sequences. It is light and may not require an immediate follow-up. It is usually translated as forcing move.
Killing or Korosu– Ensuring that a group will ultimately perish and be removed from the board.
Ko Threat — A threatening move played either to provoke an immediate response from the opponent, allowing the player to recapture the ko on his next move, or to make a gain if the opponent ignores it.
Miai — Two moves that have equivalent effects, such that if either player plays one, his opponent will play the other.
Sabaki — Development of a flexible and defensible position in an area of opposing forces, especially by means of contact plays and sacrifice tactics.
Seki — An impasse in which stones are alive without two centers because the opponent cannot or should not capture them. Also known as mutual life.
Sente — 1) The initiative; 2) a play that must be answered; 3) a play that is answered.
Tenuki — Playing elsewhere, especially breaking off from a sequence that remains to be resolved.
Tesuji — An astute, often counter-intuitive tactical play that optimally exploits a defect in the opposing shapes, literally it means the logical move in the local situation.
Tsumego — A  life and death problem.
Vital Point or Kyusho– A key point (for either player) in the local, or perhaps less commonly global, context that will normally either establish a good shape or force the opponent into bad shape.
Yose –Moves that approach fairly stable territory, typically enlarging one’s own territory while reducing the opponent’s.