Bulge
is a bulge play.
It is a hane play, backed up by the marked stone already in place to form a V. Black gains great power locally, this way. Therefore the point is the vital point here: if White takes it instead Black would start to worry about cutting points.
Once White has played the bulge point, sets up the cuts at a or b, either of which may be a good tactic. (See Bulge/Discussion)