A pet (or companion animal) is an animal kept for a person's company, as opposed to livestock, laboratory animals, working animals and sport animals which are kept for economic reasons. The most popular pets are noted for their attractive appearances and their loyal or playful personalities. Their pedigree may also be a factor.

In some cases pets may also provide their owners with benefits, such as providing companionship to elderly adults who do not have adequate social interaction with other people.

The most popular pets are dogs and cats, but there are also rodent pets, such as gerbils, hamsters, chinchillas, fancy rats, and guinea pigs; avian pets, such as canaries, parakeets, and parrots; reptile pets, such as turtles, lizards and snakes; aquatic pets, such as tropical fish and frogs; and arthropod pets, such as tarantulas, hermit crabs and scorpions.

The keeping of animals as pets can raise concerns in regard to animal welfare. In particular, overpopulation is cited as a problem, as is the breeding and treatment of animals.