A position is the arrangement of black and white stones on the go board. Position is a term used in different contexts, like positional judgement or the restriction for repetition of a position in superko rules.
The term position may also be used to refer to the distribution of stones on a specific region of the board. To avoid ambiguity one may refer to a local position or a whole board position, where appropriate (as in a superko rule).
A position can either be legal or illegal. A position is legal if and only if no strings of stones that have no liberties exist.
On the 19×19 board, there are 361 intersections. Since each of these can be either black, white, or empty, there are 3^361 (about 1.74 × 10^172) possible positions on that board. Not all of them are legal, as some of these positions contain stones with no liberties. In recent research, John Tromp and others have calculated the exact number of legal board positions that are legal. This number is about 2.08 × 10^170, or approximately 1.2% of board positions are legal. See also: Number of possible go games.