Hang gliding is an air sport in which a pilot flies a light and unmotorized foot-launchable aircraft called a hang glider (also known as Delta plane or Deltaplane). Most modern hang gliders are made of an aluminium alloy or composite-framed fabric wing. The pilot is ensconced in a harness suspended from the airframe, and exercises control by shifting body weight in opposition to a control frame, but other devices, including modern aircraft flight control systems, may be used. In the sport's early days, pilots were restricted to gliding down small hills on low-performance hang gliders. However, modern technology gives pilots the ability to soar for hours, gain thousands of metres of altitude in thermal updrafts, perform aerobatics, and glide cross-country for hundreds of kilometres. The Fédération Aéronautique Internationale and national airspace governing organizations control some aspects of hang gliding. Gaining the safety benefits from being instructed is highly recommended.

Most early glider designs did not ensure safe flight; the problem was that early flight pioneers did not sufficiently understand the underlying principles that made a bird's wing work.