Names:
There are various synonyms in the source languages and also various roman character transcriptions, so there are a bunch of names you might see, this is a list of all the variations I've seen, not necessarily exhaustive:
History:
According to the orthodox legend, Go was invented by the semi-mythical Emperor Yao in the 23rd century BCE to teach his son, Dan Zhu, to think strategically. Normally Go is referred to as "about 4000 years old." Modern scholarship suggests it more likely that the game originated in the 10th to 4th centuries BCE. Whatever the actual date, while chess has been tweaked quite a bit in the last handful of centuries, Go has remained fairly stable for thousands of years. Around 740 CE the game was brought to Japan where it became popular among the samurai and noble classes. At one point Tokugawa Ieyasu created a Ministry of Go to be headed by the winner of an annual tournament. In the Meiji Restoration era Go fell out of favor, but play was revived in Japan in the 1920's (when Japan was getting all hot and bothered by Imperialism and the good old days). Though immigrants were probably playing the game long before this without bothering to organize, the American Go Association was founded in 1937 CE. Go is currently going through a sort of renaissance. In the last decade or so, international tournaments have begun to take place and all sorts of firsts are being achieved. For example, Nai-wei Rui, a Chinese American immigrant, became the first woman to win a major national tournament in early 2000. Most of the strongest contemporary players are Korean and it is estimated that between 5%-10% of the Korean population plays the game on a regular basis.
Equipment:
Just as "tea" can be consumed in any old container but there are elaborate rules for a Japanese Tea Ceremony, a basic go board is easy to describe while a traditional set gets a bit complicated and artistic. At its heart, a go board needs a grid of spots and enough markers to fill all the spots. Full modern games are played on a 19x19 grid while 13x13 and 9x9 grids are sometimes used for teaching beginners (a Tibetan version of the game is 17x17 as are the oldest boards unearthed by archaeologists in China). In full modern games, 181 markers are used by the player who moves first and 180 markers go to the other. Notation usually runs letters left to right (skipping "i" because it looks kinda like "1") from "a" to "t" and numbers from bottom to top 1 to 19.
Here is the sort of board you could use to play by email:
a b c d e f g h j k l m n o p q r s t
19 . . . . . . . . . . . . . . . . . . . 19
18 . . . . . . . . . . . . . . . . . . . 18
17 . . . . . . . . . . . . . . . . . . . 17
16 . . . + . . . . . + . . . . . + . . . 16
15 . . . . . . . . . . . . . . . . . . . 15
14 . . . . . . . . . . . . . . . . . . . 14
13 . . . . . . . . . . . . . . . . . . . 13
12 . . . . . . . . . . . . . . . . . . . 12
11 . . . . . . . . . . . . . . . . . . . 11
10 . . . + . . . . . + . . . . . + . . . 10
09 . . . . . . . . . . . . . . . . . . . 09
08 . . . . . . . . . . . . . . . . . . . 08
07 . . . . . . . . . . . . . . . . . . . 07
06 . . . . . . . . . . . . . . . . . . . 06
05 . . . . . . . . . . . . . . . . . . . 05
04 . . . + . . . . . + . . . . . + . . . 04
03 . . . . . . . . . . . . . . . . . . . 03
02 . . . . . . . . . . . . . . . . . . . 02
01 . . . . . . . . . . . . . . . . . . . 01
a b c d e f g h j k l m n o p q r s t
A traditional set uses smooth, rounded, black slate stone for the first markers and smooth, rounded, white clamshell for the second markers. The stones should be slightly too large to fit perfectly on the board, haphazardly slapped down when placed, and not pushed into proper alignment during the course of the game so as to produce an aesthetically pleasing "organic" look by the time the game ends.
The board itself, according to tradition, should be almost but not quite square (more of that organic aesthetic) and made of wood. Black lines are etched into the surfaces and play occurs on the intersection of the lines, rather than in the squares between the lines as with chess.
The bowls that hold the stones are supposed to be oblate and wooden with lids that can be upturned to hold prisoners.
How To Play:
An unhandicapped game begins with no stones on it (in handicapped games extra stones are placed on the spots marked with "+" on the text board above). Players take turns placing stones on the board, which cannot move and remain on the board unless captured for the duration. Either player may pass at any time and when both pass the game is over.
Stones are "connected" if they are on adjacent spots in any cardinal direction but not along the diagonals. All of the spots on the board where you can add a stone such that it will be connected to stones you already have down is considered a "liberty" for the stones on the board. If a group has no liberties it is captured and removed from the board. If a stone is placed in such a way that it would immediately be captured it is a useless (or illegal, depending on Japanese or Chinese conventions) move except that: if the stone takes the last liberty away from one of the opposing groups, the opposing group dies before the new stone can be killed. Also, a player is not allowed to place a stone anywhere that would produce an identical board situation as at any point in the game. When both players pass, they figure out who has more spots on the board behind their groups of stones and the one with more territory wins.
That's all the rules. The rest is application of those rules. Here are some examples:
a b c d e f g h j k l m n o p q r s t
19 O . . . . . . . . . . . . . . . X O . 19
18 X . . . . . . . . . . . . . . . X O O 18
17 . . . X . . . . . X . . . . . . . X X 17
16 . . X O . . . . X O X . . . . + . . . 16
15 . . . X . . . . X O . . . . . . . . . 15
14 . . . . . . . . X O X . . . . . . . . 14
13 X . . . . . . . . X . . . . . . . . . 13
12 O X . . . . . . . . . . . . . . . . . 12
11 . . . . . X O . . . . . . . . . . . . 11
10 . . . + X O . O . + . . . . . + . . . 10
09 . . . . . X O . . . . . . . . . . . . 09
08 . . . . . . . . . . . . . . . . . . . 08
07 . . . . . . . . . . . . . . . . . . . 07
06 . . . . . . . . . . . . . . 8 . . . . 06
05 . . . . . . . . . . . . . 4 7 . . . . 05
04 . . . + . . . . . + . . W 3 5 6 . . . 04
03 X X X X . . . . . . . W Z 1 2 . . . . 03
02 G G G G X . . . . . . . W W . . . . . 02
01 . G . G X . . . . . . . . . . . . . . 01
a b c d e f g h j k l m n o p q r s t
Basic capturing is demonstrated in many places. If X moves at 11a, 19b, 16e, 10g, 15l, or 19t then one of O's groups will be captured.
Note especially the "behind enemy lines" capture at 19t. Contrast this with G's position in the bottom left corner of the board. When you have holes in your territory it is a good thing. These holes are referred to as "eyes" and having two of them makes the group with the eyes uncapturable. If X spends a turn putting a stone at either 01a or 01c then that stone will immediately be captured and G will be just as safe as ever. A group of stones that cannot be captured is referred to as "alive".
Another thing to note: if X moves at 10g then it would seem that O could respond by moving at 10f (right where the captured piece would be taken from) and the players could go back and forth like this forever. It is to prevent this that the rule about "no board repetition" exists. If O wants to capture at 10f she has to move somewhere else first. X would then have to make a choice: respond to O's other move or prevent O from capturing at 10f by going there himself. Of course, if X responds to the other move, then O can capture and its up to her opponent to go somewhere else before taking the piece back again... this back and forth is known as a "ko" and the wild moves all around the board are called "ko threats". Generally, a ko threat must be worth more than the ko itself, otherwise the other player will just end the ko and accept whatever losses were implied by the ko threat. I've seen games played by really advanced amateurs on IGS where a ko went on for more than 50 moves.
In the bottom right a (very simple) extended application of the rules is shown. If it is W's turn, she can place a stone at 1 (03o) and capture Z's stone at 03n. However, this would be a wasted of a move because that stone is effectively already dead: if Z moves at 1, then W moves at 2, Z at 3, W at 4 and so on. This sequence runs O across the board toward the edge where W will inevitably capture Z. This is bad for Z because each captured stone is an extra point for W and at the end of the sequence W has a large group, easy to make alive, from which to grow out and surround more territory.
Ranking:
One of the nice things about Go is that it lends itself to easy, obvious, and workable handicapping. In theory, the number of ranks between two players should equal the number of extra stones that the weaker player needs in order to give the stronger player an even game. For example, a 9kyu player should be given 2 handicap stones by a 7 kyu player to make the game even. The scale runs from about 25 kyu down to 1 kyu (lower numbers indicating greater skill) and then from amateur 1 dan to amateur 10 dan (higher numbers indicating greater skill) and then from professional 1 dan to professional 10 dan. In practice, the higher levels are very close and a whole stone's handicap is more than a levels worth. Also, professional tournament games are unhandicapped, so professionals get ranked by their records against other players of known strength.
Vocabulary:
Most of the Go terms in English are transcriptions from Japanese terminology, partly because they have a very long tradition of Japanese Go scholarship and partly because those are the terms that caught on among English speakers. There are a lot of terms, but here are the ones you are most likely to hear:
- Ko (ko rhymes with Moe of the Three Stooges): Repetitive back and forth capture. (Literally: 'eternity')
- Atari (ah-ta-ree like the game system): Like "check" in chess, except for all stones, not just the king. It means some group has only one liberty left.
- Seki (seh-kee): A situation where neither player may place the other in atari without placing herself in atari. Stalemate, with no territory awarded.
- Hane (hah-neh): A diagonal move played in contact with an enemy stone. If O moves at * below then it would be called a hane.
. . . . .
. X X * .
. O O . .
. . . . .
- Sente (sen-teh): Initiative. Some moves force a direct response. The player who is doing the forcing has sente and can play anywhere on the board that they feel like starting a sequence of moves.
- Joseki (jo-seh-kee): A known sequences of moves near the corner that result in near-equal positions for white and black. Like a gambit in chess, except you can do a different one in each corner and they start interacting as the game progresses.
- Komi (ko-mee): Score adjustment usually penalizing black for playing first. Often 5.5 points.
- Dan (just like it looks): Advanced grade.
- Kyu (just like it looks): Learner grade.
- Me (rhymes with weigh): Japanese for an eye. Two makes the group alive.