Cryopreservation is a process where cells or whole “tissuesare preserved by cooling to low sub-zero temperatures, such as (typically) 77 K or −196 °C (the boiling point of liquid nitrogen.

At these low temperatures, any biological activity, including the biochemical reactions that would lead to ,is effectively stopped. However when cryoprotectant solutions are not used, the cells being preserved are often damaged due to freezing during the approach to low temperatures or warming to room temperature.