In China it is called w�iq� (way-chee), in Korea its name is baduk, and in Japan igo (ee-go), which gave rise to the English name Go.

Simple rules
The essential rules of Go are as follows:

-	Two players, Black and White, sit at a board consisting of 19 horizontal and 19 vertical lines, giving 361 intersections.
-	Each player has a limitless number of lens-shaped tokens, called stones, of the appropriate color. The game begins with no stones on the board.
-	The players move alternatingly, with Black moving first. A move consists of a play or a pass. A play consists of placing a new stone of the player's color on an empty intersection of the board.
-	Stones that are directly adjacent to each other along the lines of the board are connected.
-	Connected stones of the same colour are considered a string of stones.
-	A string of stones has a certain number of empty intersections (termed liberties) adjacent to it along the lines of the board. If a play causes the last liberty of a string to be occupied, that string is removed from the board (captured). Strings belonging to the opponent are captured in this way before determining if any of the player's own strings are captured.
-	A play which, after any captures are completed, would recreate a previous configuration of the whole board, is illegal and cannot be played.
-	A pass allows the opponent to move again.
-	When both players pass in succession, the game ends.
-	After the end of the game, each player's score is the number of intersections that are either occupied by, or completely enclosed by, that player's stones. An empty intersection is completely enclosed by a player's stones only if all paths outward from the intersection along the lines of the grid meet the player's stones before they meet the opponent's stones.
-	The winner is the player with the greater score.

There are a small number of slight variations for these rules. These variations, are subtle, mainly affect the scoring method, and do not much change the character of the game.
In a game between players of unequal strength, a handicap is used: the weaker player starts out with a number of stones on the board.

Nature of the game
Although the rules of Go are very simple, the game itself can be extremely complex. Go is a complete-knowledge, deterministic, strategy game like chess, checkers, and reversi, although its depth exceeds even those games. Its large board and lack of restrictions allows great scope in strategy, as decisions in one part of the board are influenced by a seemingly unrelated situation in distant parts of the board, and moves made early in the game can shape the nature of conflict hundreds of moves later.

The game emphasises the importance and tensions of balance on multiple levels. To secure an area of the board, it is good to play moves close together; but to cover the largest area one needs to spread out. To ensure one does not fall behind, aggressive play is required; but playing too aggressively leaves weaknesses undefended that can be exploited. Playing too low (close to the edge) secures insufficient territory; yet playing too high (far from the edge) allows the opponent to invade. Many people find the game attractive for its reflection of the polarities found in life.

There is a theory that says no game has ever been played twice. This may be true: On a 19x19 board, there are about 4.63x10¹⁷⁰ possible positions and about 10³⁶⁰ possible games. (By contrast, the number of legal positions in chess is estimated to be between 10⁴³ and 10⁵⁰, and physicists estimate that there are not more than 10⁹⁰ protons in the entire universe.)

Traditional Go game equipment
Although one could play Go with a piece of card for a board and a bag of plastic tokens, Go players pride themselves on their game sets. The traditional Go board (called a goban in Japanese) is solid wood, about 15-20cm thick, preferably from the rare golden-coloured Kaya tree, and stands on its own attached legs. Players sit on reed mats (tatami) on the floor to play. The stones (go-ishi) come in matching solid wood pots (go-ke) and are made out of clamshell (white) and slate (black) and are extremely smooth. The natural resources of Japan have been unable to keep up with the enormous demand for the native clams and slow-growing Kaya trees; both must be of sufficient age to grow to the desired size, and they are now extremely rare at the age and quality required, raising the price of such equipment tremendously.

In clubs and at tournaments, where large numbers of sets must be maintained (and usually purchased) by one organisation, the expensive traditional sets are not usually used. For these situations, table boards (of the same design as floor boards, but only about 2-5cm thick and without legs) are used, and the stones are made of glass rather than slate and shell. Bowls will often be plastic if cheap wooden bowls cannot be had. Plastic stones can be had, but are considered inferior to glass as they are generally much lighter, and most players find them too unpleasant to justify the difference in price.

The dimensions of the board (traditionally the grid is 45.45cm long and 42.42cm wide, with space beyond to allow stones to be played on the edges and corners of the grid) often surprise newcomers: it is not a perfect square, but is longer than it is wide, roughly in the proportion 12:11. Two reasons are frequently given for this. One is that when the players sit at the board, the angle at which they view the board gives a foreshortening of the grid; the board is slightly longer between the players to compensate for this. Another reason is that the Japanese aesthetic finds any structure which is perfectly symmetrical to be in bad taste, and the board is not made a perfect square for this reason.

Traditional stones are made so that black stones are slightly larger in diameter than white; this is probably to compensate for the optical illusion created by contrasting colours that makes the white stones appear larger on the board than black stones. The difference is slight, and since its effect is to make the stones appear the same size on the board, it can be surprising to discover they are not.

The bowls for the stones are of a simple shape, like a flattened sphere with a level underside. The lid is loose-fitting and is upturned before play to place opponent's stones captured during the game. The bowls are usually made of turned wood, although small lidded baskets of woven bamboo or reeds make an attractive cheaper alternative.

There is even an art to placing a Go stone, held between the tips of the outstretched index and middle fingers and striking the board firmly to create a sharp click. Many consider the acoustic properties of the wood of the board to be quite important. The traditional goban will usually have its underside carved with a pyramid called a Heso recessed into the board. Tradition holds that this is to give a better resonance to the stone's click, but the more conventional explanation is to allow the board to expand and contract without splitting the wood. A board is seen as more attractive when it is marked with slight dents from decades -- or centuries -- of stones striking the surface.

History
The origins of the game are unknown, but the oldest surviving references come from China in the 6th century BC. Except for changes in the board size and starting position, has essentially kept the same rules since that time, which quite likely makes it the oldest board game still played today. It had reached Japan by the 7th century, and gained popularity at the imperial court in the 8th. By the beginning of the 13th century, the game was played in the general public in Japan.

Early in the 17th century, the then best player in Japan, Honinbo Sansa, was made head of a newly founded Go academy (the Honinbo school, the first of several competing schools founded about the same time), which developed the level of playing greatly, and introduced the martial-arts style system of ranking players. The government discontinued its support for the Go academies in 1868 as a result of the fall of the Tokugawa shogunate.

In honour of the Honinbo school, whose players consistently dominated the other schools during their history, one of the most prestigious Japanese Go championships is called the "Honinbo" tournament.

Historically, Go has been unequal in terms of gender. However, the opening of new, open tournaments and the rise of strong female players, most notably Rui Naiwei, has in recent years legitimised the strength and competitiveness of emerging female players.

External links and references Go can be played on the Internet against opponents from around the world on numerous Go servers. Kiseido Go Server is such a server, complete with easy-to-use interfaces/clients and introductory material. goproblems.com has over 1000 problems for practice in a realistic Java applet. Sensei's library is a wiki devoted entirely to the game of Go - it even has special markup for displaying Go patterns. How To Play Go. Samarkand is owned by Janice Kim 1p and has a very good beginner introduction. The Usenet newsgroup rec.games.go has its own FAQ document, The rec.games.go FAQ. For more on the history of Go, see http://gobase.org/history/. The popular SGF file format is used to exchange Go lessons and recorded games. Several free reading and authoring programs are listed at http://gobase.org/sgfeditors.html. http://gobase.org/ hosts a database of professional Go games in SGF file format. Amateur games are reviewed at The Go Teaching Ladder. Elwyn Berlekamp, David Wolfe: Mathematical Go. A K Peters; ISBN 1568810326

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Go_(board_game)".