How do bats navigate in complete darkness?

Bats are the best-known mammals to use echolocation, a biological sonar system. They produce calls, often through the mouth or nose, and the returning echoes give them information about distance, direction, size and even the texture of objects. This ability is especially important for insect-eating bats that hunt at night, though some species also use vision and smell. Scientists have studied bat echolocation for more than a century, and it has inspired technologies such as sonar and some kinds of navigation research.