A pet is an animal kept for companionship and enjoyment or a household animal, as opposed to livestock, laboratory animals, working animals or sport animals, which are kept for economic reasons. The most popular pets are noted for their loyal or playful characteristics, for their attractive appearance, or for their song. Pets also generally seem to provide their owners with non-trivial health benefits; keeping pets has been shown to help relieve stress to those who like having animals around. There is now a medically-approved class of "therapy animals," mostly dogs, that are brought to visit confined humans. Walking a dog can provide both the owner and the dog with exercise, fresh air, and social interaction.

Local restrictions

Many cities and towns have local ordinances limiting the number of pets a person may have, and may also restrict or forbid certain pets (such as fowl or exotics). Certain breeds of dog, such as pit bulls and rottweilers, are banned in some places. Dog/other canid/wolf mixes are also banned in some places.

The cities of Berkeley, California and Boulder, Colorado have passed laws stating that people who have pets do not "own" them; rather, they are the pet's "guardian."

Condominium associations and rental properties often ban animals because of the smells and noise the animals create.