This is one important technique, known since the seventeenth century, for playing against the small high enclosure.
Naturally it is much affected by any stones present on the left or upper sides.
is likely, but Black may play one space below in order to provoke an atari.
That is , Black can regard this variation as better, in some circumstances, since the aji of White's peep at a is less serious. Of course this depends on how Black intends to handle the centre, subsequently.