It is believed that domestication started in 12000 BC when human domesticated Dog as their Pet animal. Dog is a domestic mammal of the family Canidae a subspecies of the gray wolf (C. lupus) and related to foxes and jackals.

Dog has been the most widely kept working, hunting, and companion animal in human history but nowadays dogs perform many roles such as hunting, herding, pulling loads, protection, assisting police and military. Dog's value to early human hunter-gatherers led to them quickly becoming ubiquitous across world cultures. The dog has evolved from the gray wolf into more than 400 distinct breeds. In 2001, there were estimated to be 400 million dogs in the world. They are able to thrive on a starch-rich diet and vary widely in shape, size and colours. Siberia and Europe are the two places where domestication may have occurred initially. Later is spread to other countries. The earliest archaeological evidence of dog-like canids in North America dates from about 9,000 years ago. In ancient Egypt, dogs were thought to possess godlike characteristics.

It is estimated the pet dogs are uncommon in the world as three-quarters of the world's dog population in the developing world lives as feral, village, or community dogs. ELites keep dogs as their companions and it has a long history. Pet dog populations grew significantly as suburbanization increased after World War II. In the 1950s and 1960s, dogs were kept outside more often in the doghouse than they tend to be today. Their primary function at that time was to act as a guard, children's playmate, or walking companion. There have been an increased role of dogs in the emotional support of their human guardians from the 1980's. There are a vast range of goods, services and places available to transform a pet dog into an ideal companion. This could be anything from dog perfumes, couture, furniture and housing, to dog groomers, therapists, trainers and caretakers, dog cafes, spas, parks and beaches.

Dogs have the same five senses as humans. However, some are more highly developed and some are less. Dogs’ sense of smell is by far the most acute and is immeasurably better than that of humans. In disadvantages, the dog’s sense of taste is poorly developed compared with that of humans. They also have poor colour perception. Dogs have same response to voices and use the same parts of the brain as humans do was shown in a latest study using magnetic resonance imaging (MRI) comparing humans and dogs which make them friendly social pets to humans. A 2005 paper states "recent research has failed to support earlier findings that pet ownership is associated with a reduced risk of cardiovascular disease, a reduced use of general practitioner services, or any psychological or physical benefits on health for community dwelling older people. Research has, however, pointed to significantly less absenteeism from school through sickness among children who live with pets."