Humans have bred many species for domestication, including livestock such as sheep and pigs, as well as pets such as dogs and cats. Dogs were the first animals to be domesticated.
Although the earliest domestication processes are unknown, it is likely that dogs and cats began living around humans due to the availability of food. Early humans saw that dogs could be used for guarding camps and hunting, and that cats helped reduce the populations of disease-carrying rodents.
Humans domesticated many livestock species for food. Cattle and goats were domesticated for their meat and milk. Sheep provide wool and meat, and chickens and other poultry provide meat and eggs.
Another class of domesticated animals are those used for travel or plowing. Horses and donkeys are common examples of this, although horses may have been initially domesticated for meat. Hybrid offspring of those two species, known as mules, are also bred by humans. Oxen and camels are also examples of domesticated animals used to carry burdens.
Humans sometimes keep pets or tame wild animals that are not fully domesticated. For example, pet reptiles such as snakes are not domesticated, nor are ostriches or honeybees.
Some unusual animals have also been domesticated. For example, silkworms were domesticated over 5,000 years ago in China. Goldfish, pigeons and some types of mice are domesticated, as well as some populations of silver foxes.