This document discusses how various animals use echolocation and ultrasound. It provides examples of bats, dolphins, whales and some insects that use echolocation to navigate and find prey. They do this by emitting click sounds or ultrasound and listening to the echoes. The document also discusses how humans are now using echolocation and ultrasound technology for applications like driverless cars, assistive devices for the blind, and robotics. One example highlighted is a blind boy named Ben Underwood who taught himself to use echolocation to navigate and do activities like ride a bike.