Ice sculpture is a form of sculpture that uses ice as the raw material. Sculptures from ice can be abstract or realistic and can be functional or purely decorative. Some ice carvers use colored ice blocks produced by adding dyes into the ice, or the combination of clear and colored ice to accomplish a certain effect. Ice sculptures are generally associated with special or extravagant events because of their limited lifetime. The lifetime of a sculpture is determined primarily by the temperature of its environment and thus, a sculpture can last from mere minutes to possibly months. There are several ice festivals held around the world, hosting competitions of ice sculpture carving.