A Taser or conducted electrical weapon (CEW) is an electroshock weapon sold by Axon. It fires two small dart-like electrodes, which stay connected to the main unit by conductors, to deliver electric current to disrupt voluntary control of muscles causing "neuromuscular incapacitation". Someone struck by a Taser experiences extreme pain and over-stimulation of sensory nerves and motor nerves, resulting in strong involuntary muscle contractions. Tasers will incapacitate, not just cause pain compliance, and are thus preferred by some law enforcement over non-Taser stun guns and other electronic control weapons, which, like a Taser when used solely in "Drive Stun" mode, can only do the latter.
Tasers were introduced as non-lethal weapons for police to use to subdue fleeing, belligerent, or potentially dangerous people, who would have otherwise been subjected to more lethal weapons such as firearms. A 2009 Police Executive Research Forum study said that officer injuries drop by 76% when a Taser is used. However, while Taser CEO Rick Smith has stated that police surveys show that the device has saved 75,000 lives, there have been instances where Tasers have resulted in serious injury or death. Although some other companies have produced similar devices (e.g., Raysun X1), their significance as of 2014 is still marginal.
Jack Cover, a NASA researcher, began developing the Taser in 1969. By 1974, Cover had completed the device, which he named after his childhood hero Tom Swift (book "Thomas [A] Swift's electric rifle", by "Victor Appleton", a house pseudonym of the Stratemeyer Syndicate). The Taser Public Defender used gunpowder as its propellant, which led the Bureau of Alcohol, Tobacco and Firearms to classify it as a firearm in 1976. The backformed verb "to tase" is used sometimes.