However, it would be helpful to know that to peep is a very powerful tactic in Baduk. With a peep, you can do something, or make a shape, which requires more than one move.
Black wants to envelop the white group on the side and build a wall toward the center. However, because the gap between the two △-marked black stones is wide, it seems impossible to block in the white stones. In this case, the peeping technique becomes useful.
Peeping is a move placed adjacent to a threatened cutting point; Black 1 here, threatening the cutting point at ▲, is such a move. While White has to defend the cutting point with 2 rather than going out to the center, Black can play the two moves 1 and 3, which reduce the breach in the blockade. If White bends at A instead of 6, Black will cut at 6.
If your peep threatens two cutting point at the same time, as Black 3 does to A and B here, you can cut either of them. Note that to play Black 1 is the right order of moves.
The corner territory of White seems well-kept, but Black can live inside by two consecutive peeps.
As you may guess, the first peep is Black 1. If White connects at 2, Black will peep again at 3. Then, up to Black 11, Black can easily make two eyes in the corner, which seemed to be White’s territory.
If White doesn’t connect as in Dia.5 but blocks with 2, Black 3 is still a good move. With the help of this move, Black can play 5 which aims to bridge under with 9, and cut with 6 as well. Up to 9, Black succeeds in reducing White’s territory enormously, and also leaves a good follow-up at A.
Although peeping is a powerful technique, it is not always easy to use it correctly. Since a peep is usually a sente, as the moron proverb implies, people often play a peep without any particular purpose. However, oftentimes, a peep doesn’t do any good to the player but rather strengthens the opponent’s shape. Also, there is a specific way to peep in a certain situation.
In order to deprive an eye-shape of the white group on the upper side, Black wants to peep the cutting point at A. What would be the correct move?
Black 1 is the easiest way to peep, but it leaves White the potential to peep at ▲, aiming at both A and B.
In this situation, Black 1 is the correct way of peeping, which prevents White’s peeping with ▲ as in Dia.8. The attempt of White to defend the cutting point in sente through exchanging White A and Black B would just allow Black to peep again with C and remove White’s possible base.
The writer is a baduk professor at Myongji University and a professional player of the game.