There is Death in the Hane
This proverb, "There is death in the hane", refers to the fact that the hane is a very common method of killing groups. The main purpose of the hane is to reduce the space for making eyes.
Example 1
The hane at kills the Black group with a bulky five dead shape. If Black tries to capture at a, this does not gain an eye, and White can block Black's escape at b.
Example 2
For example, this Black group (an L+1-group) can be killed with the hanes at and
. If Black blocks at a, it will turn Black's interior space into a dead bulky five. White can then kill Black with a placement tesuji at b.
Notice that in the above examples, the hane stone is not defended when put into atari. Instead another hane or a placement follows. That is because the capturing the hane stone will get a false eye.