Echolocation, also called bio sonar, is a biological sonar used by several animal species. Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects. Echolocation is used for navigation, foraging, and hunting in various environments.

Echolocating animals include mammals, most notably Laurasiatheria, especially odontocetes (toothed whales) and some bat species, and also, using simpler forms, species in other groups such as shrews. A few bird species also echolocate, including two cave-dwelling bird groups, the so-called cave swiftlets in the genus Aerodramus (formerly Collocalia) and the unrelated oilbird Steatornis caripensis.