A litter is a stretcher designed to be used where there are physical obstacles that impair movement, including other hazards such as, in confined spaces, on slopes or uneven terrain, or in densely forested areas. Typically it is shaped to accommodate an adult in a face up position and it is used in search and rescue operations. The person is strapped into the basket, making safe evacuation possible. The person generally is further protected by a cervical collar and sometimes a long spine board, so as to immobilize the person and prevent further injury.
A litter essentially is a stretcher with sides (or just a raised edge) and a removable head and/or torso cover. They are most notably remembered from Korea and Vietnam images of United States Air Force Pararescue airmen or more recent Coast Guard video clips of helicopters rescuing injured people from isolated areas. Some will also recall the images from the TV shows Emergency! and M*A*S*H of fixed stretchers on either side of medical evacuation helicopters.
One widely used style of litter is the Stokes basket.