Most snakes have an excellent sense of smell, in part to make up for their poor eyesight and limited hearing.
Rather than a conventional nose, however, snakes sniff with an organ at the roof of the mouth called a Jacobson's organ, which is also found in a few lizard species.
Snakes flick their tongues to collect scent particles for this organ. The prongs of the forked tongue is stuck into a pair of holes in the Jacobson's organ. The snake's nostrils also play a supporting role.