Cryopreservation is the ultra-low temperature storage (usually in liquid nitrogen at ca. -135 to -196?C) of living cells, tissues and organs capable of resuming normal functions after retrieval from a cryobank. This chapter explains the basic principles of cryopreservation with respect to strategies currently used to cryoprotect the diverse biological materials held in cryogenic storage. Approaches used to minimize or obviate the lethal and sublethal effects of cryoinjury are particularly highlighted. Examples of how cryopreservation has been universally applied to safeguard and preserve the wide spectrum of biological resources used in agriculture, biotechnology, healthcare, and biodiversity conservation are summarized and general guidance is offered for the management of bioresources in cryobanks.