A pet is an animal that is kept for companionship and enjoyment, as opposed to livestock, laboratory animals, working animals or sport animals, which are kept for economic reasons or to perform specific jobs. The most popular pets are noted for their loyal or playful characteristics or for their attractive appearance or song. Pets can provide their owners with many health benefits. The keeping of pets has been shown to help remove stress. Walking a dog can also provide its owner (as well as the dog) with exercise, fresh air, and the opportunity for social interaction.
While in theory one could keep any animal as a pet, in practice a small number of species of mammals, especially dogs and cats, and other small animals, such as birds, have dominated the list of species kept as pets for a very long time. Fish have joined them more recently. Many of these animals are domesticated, while others, such as reptiles, are often considered exotic pets. The glofish, a genetically modified zebrafish with a bright red fluorescent color, is the first genetically modified (GM) animal to be engineered as a pet.
The captive gorilla Koko is one of few examples of a non-human animal which has had a pet. Koko's first pet was a kitten named All Ball.
A pet can be acquired from a pet store, an animal shelter, a breeder, and sometimes from people who have extras due to births. See also Dog adoption.
Sometimes people treat their pets like they are children, especially when the people do not have children or their children are grown up.
The domestication of animals is the oldest documented keeping of animals in captivity. The result was habituation of wild animal species to survive in the company of, or by the labor of, human beings. Domesticated species are those whose behaviour, life cycle, or physiology has been altered as a result of their breeding and living conditions under human control for multiple generations. Probably the earliest known domestic animal has been the dog, likely as early as 15000 BC among hunter-gatherers in several locations.
Throughout history not only domestic animals as pets and livestock were kept in captivity and under human care, but also wild animals. Some were failed domestication attempts. Also, in past times, primarily wealthy men, aristocrats and kings collected wild animals for various reasons. Contrary to domestication, the ferociousness and natural behaviour of the wild animals were preserved and exhibited. Today's zoos claim other reasons for keeping animals under human care: conservation, education and science.
Captive animals, especially those which are not domesticated, sometimes develop repetitive, apparently purposeless motor behaviors called stereotypical behaviors. These behaviors are thought to be caused by the animals' abnormal environment. Many who keep animals in captivity, especially in zoos and related institutions and in research institutions, attempt to prevent or decrease stereotypical behavior by introducing novel stimuli, known as environmental enrichment.
In veterinary medicine, dogs and cats are often considered "common" pets, while all other animals are grouped into either "farm animals" (such as horses, cows, sheep) and "exotics" (including pocket pets, birds, reptiles).
Animal protection advocates try to call attention to the "pet overpopulation crisis" in the United States. According to the Humane Society of the United States, 3-4 million dogs and cats are euthanized each year in the country and many more are confined to cages in shelters because there are many more animals being born than there are homes. This crisis is created by non-spayed/neutered animals reproducing and people intentionally breeding animals. In an average year a fertile cat can produce three litters of kittens, with up to 4 to 6 kittens in each litter. Based on these numbers, one female cat and her offspring could produce up to 420,000 cats over a seven year period if not spayed or neutered. There are also major overpopulation problems with other pet species, such as birds and rabbits. Local humane societies, SPCA's and other animal protection organizations urge people to spay or neuter their pets and to adopt animals from shelters instead of purchasing them from breeders or pet stores.