Stasis refers to a complete cessation of movement within an area.
If used when referring to lifeforms, it is also known as suspended animation and denotes the limiting of bodily functions, inducing a prolonged sleep, in order to slow down the aging process. Most often this is accomplished through cryogenic stasis.
Individuals put into stasis are usually placed in a stasis unit, and can result in being successfully suspended for hundreds of years while being less susceptible to environmental hazards. (TNG: "The Emissary", "Relics", "Face of the Enemy"; VOY: "The 37's", "One", "Dragon's Teeth"; ENT: "Precious Cargo") Pre-warp civilizations therefore sometimes use sleeper ships equipped with stasis technology for long-range transport of personnel, usually as colony vessels. (TOS: "Space Seed"; TNG: "Face of the Enemy")
Some years prior to 2372, Starfleet used artificial environments for people held in stasis on long deep space voyages. The technology held the mind inside a mental landscape to keep it active. In 2353, the Kohl, in the Delta Quadrant, utilized a similar technology in their hibernation pods. (VOY: "The Thaw")
Suspended animation was also employed as a security measure. Before the Cardassians abandoned their space station Empok Nor in 2372, they left behind in stasis three soldiers of the Third Battalion, First Order. Their stasis tubes, having been programmed to revive them should power be restored to the station, the soldiers – under the influence of psychotropic drugs designed to heighten their natural xenophobia – attempted to kill a Starfleet salvage team sent from Deep Space 9 in 2373. (DS9: "Empok Nor")
In 2371, following the Kai election, Vedek Bareil joined Kai Winn as her key advisor in negotiating the Bajoran-Cardassian Treaty. Just before the signing of the treaty, he was injured in a plasma explosion on board a Bajoran Transport vessel. Dr. Julian Bashir was able to bring him back from the brink of death. However, Bareil refused life-saving treatment in order to complete the negotiations since Kai Winn was not experienced enough to handle the Cardassians by herself. Dr. Bashir told him that he should be placed in stasis for an undetermined period of time so his injuries could heal. (DS9: "Life Support")
During the Dominion War, it was learned that the Dominion shipped Jem'Hadar infants in stasis chambers. This was discovered 2371 when Quark inadvertently purchased a Jem'Hadar infant in a stasis chamber that was included in salvage. (DS9: "The Abandoned")
Harry Kim recalled the tale of his uncle Jack, who piloted a mission to Beta Capricus in 2210, while the rest of the crew was in stasis. When he arrived it turned out that Beta Capricus did not exist, but was indeed just the misinterpreted image of a distant galaxy. Jack did not wake his crew because there was nothing to do or see and returned to Earth. When they arrived six months later, Jack brought the crew out of stasis and they wondered why they hadn't left Earth's orbit. (VOY: "11:59")