The pattern behind is one of the first to occur to a beginner. The initial shape resembles a chapel, hence the name. [1]
It is one of the basic edge patterns.
The white stones are captured. This is in fact also an example of a ladder.
So, the beginner learns that the descent doesn't save the stones. That does not alter the fact that
is sometimes a good move, in particular to destroy eye shape. In some cases, neighbouring white stones mean
can save the original stone.
[1] If people know of existing names for the shape, please rename and rearrange the pages.
When I learned this pattern as a beginner, we called it the "second line trap" -- for obvious reasons. -- Michael Eisenberg