Answer:
The goals of cryonics are to preserve humans and animals in cryogenic temperatures for decades or centuries (if necessary) until the technology exists to repair all of the damage that must be repaired to restore the humans or animals to youthful healthy life. Because people who are cryonically preserved are generally old and diseased, an essential part of cryonics working is that all diseases will have been cured and that people can be rejuvenated to a youthful condition. Cryonics is viewed as an ambulance (or time-capsule) to future medicine. Although cryonics may not work, there is also a chance that it will work, and if it does, the payoff will be hundreds or thousands of years of youthful life in an exciting future world.