A pet is an animal kept for companionship and enjoyment or a household animal, as opposed to wild animals or to livestock, laboratory animals, working animals or sport animals, which are kept for economic or productive 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.
Pets have the ability to stimulate their caregivers, in particular the elderly, giving people someone to take care of, someone to exercise with, and someone to help them heal from a physically or psychologically troubled past. Having a pet may help people achieve health goals, such as lowered blood pressure, or mental goals, such as decreased stress. There is evidence that having a pet can help a person lead a longer, healthier life. In a study of 92 people hospitalized for coronary ailments, within a year 11 of the 29 without pets had died, compared to only 3 of the 52 who had pets. A recent study concluded that owning a pet can reduce the risk of a heart attack by 2% and that pets are better than medication in reducing blood pressure. Owning a pet can also prolong survival of a heart attack. Dogs which are trained to be guide dogs can help people with disabilities.
Domesticated pets are the most common types of pet. They have consistently been kept in captivity over a long enough period of time that they exhibit marked differences in behavior and appearance from their wild relatives.