A fictional form of incapacitating agent, sometimes known as "knockout gas", has been a staple of pulp detective and science fiction novels, movies and television shows. It is presented in various forms, but generally is supposed to be a gas or aerosol providing a harmless way of rendering characters quickly and temporarily unconscious without physical contact. (This is in contrast to chloroform, a liquid anesthetic — itself a common element in genre fiction — which requires physically subduing a victim before being applied.)