When a writer compares things using the words like or as, it is a simile.

EXAMPLES (from an online collection, Anonymous):

Comparisons using LIKE:	Comparisons using AS:
He fell for her like his heart was a mob informant, and she was the East River.	He was deeply in love.  When she spoke, he thought he heard bells, as if she were a garbage truck backing up.
Her hair glistened in the rain like a nose hair after a sneeze.	Her vocabulary was as bad as, like, whatever.