Now you know how to tell the score at the end of the game. But how do you know when the game ends? It's simple: When you play, you can choose to "pass" if you want. That is, not play any stone at all. When you have played long enough, you will eventually get to a position where you know that you can't make any more points. If you play a stone, you will either be playing inside your own eyes (which isn't worth any points, since an eye and a living stone are both worth the same amount), or else you will be playing in your opponent's eyes, where they will just capture your stones. When this is the case, you should pass. When both players pass, the game ends and you tally up the score.