Pets commonly provide their owners physical and emotional benefits. Walking a dog can supply both the human and pet with exercise, fresh air, and social interaction. Pets can give companionship to elderly adults who do not have adequate social interaction with other people.Nature, in the broadest sense, is equivalent to the natural, physical, or material world or universe. "Nature" refers to the phenomena of the physical world, and also to life in general. It ranges in scale from the subatomic to the cosmic. The study of nature is a large part of science. Although humans are part of nature, human activity is often understood as a separate category from other natural phenomena.