Carbonite is a metal alloy that, when mixed with various gasses, can be used to flash freeze blocks of cargo for transportation or storage. Its use in freezing living creatures is relatively new in the galaxy and considered highly dangerous--subjects frozen for more than a few hours have a very low survival rate unless the carbonite is prepared with much expense at an elaborate facility. Even in the best cases, the sudden shock of flash freezing (often combined with a lack of life-support monitoring during suspension) tends to make the process extremely traumatic--sometimes even turning fatal hours after a subject has been thawed.
Still, a quick carbonite spray is the only known technique for freezing living creatures quickly and with minimal preparation. The technology is growing increasingly popular with bounty hunters and smugglers; as a result, many bounty hunting guilds have clauses in their contracts mandating live capture payment even if the bounty fails to survive the post-hibernation period.