Cryogenics, or "cryonics," refers to freezing a human being - who is either near death or within minutes after death -- at subzero temperatures to preserve the body. The idea is that the body can be revived and made healthy in a future where medical technology has advanced to the point there the subject can be cured of the disease that killed him.
The term "cryonics" was coined by Karl Werner in the 1960s and popularized by R.W. Ettinger in The Prospect of Immortality (1966). But the idea didn't catch fire with the public. When Fred Pohl asked Ettinger how cryonics was going, Ettinger replied, "Many are cold but few are frozen."
The Cryonics Society of California began freezing people in 1967. Baseball great Ted Williams was one of them, causing some controversy among his children. There's a rumor that Walt Disney had his body frozen immediately after death and preserved in a cryogenic chamber, so that if medical technology develops to the point where it can cure the disease that killed him, he could be brought back to life.
The first fictional use of cryonics was W. Clark Russell's The Frozen Pirate (1887) followed by Louis Boussenard's 10,000 Years in a Block of Ice (1889) in which a contemporary man visits the future. Other SF works that use cryogenics as a means of visiting the future include Frederik Pohl's The Day of the Pussyfoot (1969), Mack Reynold's Looking Backward, From the Year 2000 (1973), and Woody Allen's film Sleeper (1973).
Other science fiction stories with a cryogenic theme include Clifford Simak's Why Call Them Back from Heaven (1967), Ernest Tidyman's Absolute Zero (1971), and A.A. Attanasio's Solis (1994) in which cryogenically preserved corpses are revised to serve as cheap labor. Fred Pohl and Larry Niven coined the term "corpsicle" to describe people whose cryogenically frozen bodies are mined for spare parts -- Pohl in The Age of Pussyfoot (1969) and Niven in A World Out of Time (1976).