Tiger's Mouth in Go — The Hanging Connection Shape | PlayGo.gg

A situation where if your opponent were to play inside the tiger's mouth, they would be putting themselves in atari.

What is a tiger's mouth?

Three friendly stones form a tiger's mouth when they sit on the three points around a single empty intersection — like a V or a bracket open toward one direction. The empty point in the middle is the mouth. If the opponent plays into the mouth, that lone stone has only one liberty and is in immediate atari, so the three stones behave as one group without ever touching.

The shape is also called a hanging connection (kaketsugi): connection by threat of capture rather than by physical contact. Don't confuse it with a real eye — an eye is a point the opponent can never legally fill, while a tiger's mouth can be played into; the move just loses the stone immediately. A tiger's mouth contributes to safety but does not count as one of the two eyes a group needs to live.

When to use a tiger's mouth?

Compared with a solid connection (placing a stone directly on the cutting point), the tiger's mouth has two advantages:

1. Efficiency. Same one stone, but it lands one line further out, projecting more influence. 2. Shape. A tiger's mouth keeps the group's outline rounder and harder to attack. A solid connection is heavier — fine when you need certainty, wasteful when the cut isn't actually threatened.

Example of a tiger's mouth in a game

Which moves give you a tiger's mouth?

Tiger's mouth is a good shape to know for beginners. They are also fundamental to puzzles. I would not recommend doing these puzzles unless you are of that rank - for beginners they are too hard, but feel free to check them out!