The Rules of Go

Page 03
About Surrounding

As we have already mentioned, the goal of the game is to surround things. Each empty intersection you surround counts as one point. Each opponent stone you kill also counts as one point. Lets look at some examples.

Position 1	Position 2

Fig 1. Surrounding basics

In Position 1 of Fig 1 you can see some areas surrounded by Black (the areas around 'a' and 'c') and White (the area around 'b'). The upper right corner is unclaimed as yet - it is neither Black's nor White's area - they have yet to fight it out who will get more points there. So, for now, we can do a preliminary count which gives 15 points for Black (6 in upper left around 'c' plus 9 in lower right around 'a') and 17 points for White (all of them in lower left around 'b'). So there is 2 points difference in White's favor. This is not a decisive advantage, and so the game will be decided by what happens in the upper right corner.

Position 2 of Fig 1 illustrates the concept of prisoners. All the triangled White stones are entirely surrounded by the Blacks. Thus they are removed from the board and treated as prisoners. Each of them is worth 1 point towards Black's score. An important idea is here that stones need to be entirely surrounded before being declared prisoners. For example, the 3 Black triangled stones in upper left corner are not yet fully surrounded since they still have a breather at 'a' - White has to play there to kill the three Black stones.

Some important concepts related to the idea of killing stones are discussed here.

Additional Comments

Note on Prisoners:
The prisoners are removed from the board and the one who caught them keeps them. They will be needed to calculate the final score. So, in this way, a prisoner is often seemingly worth 2 points, not one - the point for the actual prisoner, plus the point of territory created after the prisoner has been removed.

Hint:
It is usually a better idea to concentrate on surrounding areas to make territory rather than trying to surround opponent's stones to gain prisoners. A typical result of a 19x19 board game may be White: 63 point in territory plus 4 points in prisoners vs. Black: 67 points in territory plus 2 points in prisoners. So, as you can see, the territory usually plays a much larger role in determining the score, so it seems to be a good idea to concentrate on maximizing it.; The reason for the territory to be so overwhelmingly dominant with respect to the final score is that it is much easier to surround empty space (which does not run away) than it is to surround enemy stones (which run and defend themselves).