GO

Go is a board game for two players, noted for being rich in strategic complexity despite its simple rules.

The game is played by two players who alternately place black and white stones (playing pieces, now usually made of glass or plastic) on the vacant intersections of a grid of 19×19 lines. The object of the game is to control a larger portion of the board than the opponent. A stone or a group of stones is captured and removed if it has no empty adjacent intersections, the result of being completely surrounded by stones of the opposing color.

Placing stones close together helps them support each other and avoid capture. On the other hand, placing stones far apart creates influence across more of the board. The strategic difficulty of the game stems from finding a balance between such conflicting interests. Players strive to serve both defensive and offensive purposes and choose between tactical urgency and strategic plans.

Go originated in ancient China more than 2,500 years ago, and although it is not known exactly when the game was invented, by the 3rd century BC it was already a popular pastime, as indicated by a reference to the game in the Analects of Confucius. Archaeological evidence shows that the early game was played on a board with a 17×17 grid, but by the time that the game spread to Korea and Japan in about the 7th century boards with a 19×19 grid had become standard.

The game is most popular in East Asia, but has gained some popularity in other parts of the world in recent years. A conservative estimate places the number of Go players worldwide at approximately 27 million.[1] Go reached the West through Japan, which is why it is commonly known internationally by its Japanese name.

Go was introduced to both Japan and Korea—where it is called baduk somewhere between the 5th and 7th centuries AD, and was popular among the higher classes. In Korea, the game was developed into the variant called Sunjang baduk by the 16th century. Sunjang baduk became the main variant played in Korea until the end of the 19th century.

In Japan—where it is called go or igo the game became popular at the Japanese imperial court in the 8th century, and among the general public by the 13th century. In 1603, Tokugawa Ieyasu re-established Japan's unified national government. In the same year, he assigned the then-best player in Japan, a Buddhist monk named Nikkai (né Kanō Yosaburo, 1559), to the post of Godokoro. Nikkai took the name Honinbo Sansa and founded the Honinbo Go school.[27] Several competing schools were founded soon after. These officially recognized and subsidized Go schools greatly developed the level of play and introduced the dan/kyu style system of ranking players.

Players from the four schools (Honinbo, Yasui, Inoue and Hayashi) competed in the annual castle games, played in the presence of the shogun.