Oklahoma State University lists 72 breeds of domestic pigs on its Breeds of Livestock Project website. "Pig" can also refer to any animal of the 10 species in the genus Sus, which includes domestic pigs.
Domestic pigs are a subspecies of the Eurasian wild boar, Sus scrofa. They have been bred for meat since prehistoric times. They also supply leather and bristles. Some small breeds are kept as pets. Pigs have also been used for hunting truffles, in medical research and in primitive waste disposal systems. Wild pig species are important prey animals for large carnivores in their regions and are also hunted by humans.