Cats use their whiskers for a wide variety of reasons. The primary use is to help a cat judge whether or not he'll fit through an opening. Another reason is navigation, because the whiskers are so sensitive they help detect the slightest directional change in a breeze. In addition to having sensory properties, a cat's whiskers are also a good indicator of his mood. When a cat is angry or feels defensive, the whiskers will be pulled back and when happy, curious or content, the whiskers will be more relaxed and pushed forward.