Go is played on a 19x19 grid of lines. Players alternate placing black and white stones on the intersections of the lines, with the black player going first. A liberty is a free space around a placed stone. liberties can only be in the North, south, east, and west directions. So a solitary stone will have 4 liberties. A stone is dead and removed from the board when it has 0 liberties. If you place two stones of the same color next to each other (north,south,east,west) then they will combine their liberties, we call this entity a string. Once the string has 0 liberties, all the points that belong to the string are removed from the board. A player can pass at any time.

You cannot put a stone down where it would immediately die (ie: if you try to place it at a spot that is surrounded on the NWSE by the opposition). The only exception to this rule is that if you place a stone down in the middle of an enemy area, but by placing this stone you kill the enemy area (by making it's liberties 0), then it's ok to place the stone (figure 1). Lastly, you cannot place a stone which would take you back to the previous board position (figure 2). This is to ensure that each move makes some progress towards an end of the game.

Unlike chess, where there is an easily identifiable end to the game - when the king is captured - a game of go ends when both players pass in succession. The scoring can be done in a few different ways, but the basic elements are: points that you have on the board are counted, stones of the enemy that you have killed are counted, and areas of the board which are controlled by you are counted. If an area is debated as to if who has control over it, then the player shouldn't have passed but played in the debated area.

In review: you can place a stone on any intersection except for a suicide, or an spot that will take you back to board you just were at. White and black players keep placing stones until both players pass. Score is then calculated.