Dogs vary in sizes, colors, coat types, and shapes. It is found everywhere, in every nook and corner of the world. Dogs are animal that have lived with people as pets for more than 10,000 years; longer than any other animal. During that time, breeders have developed about 400 breeds to perform various tasks, such as providing companionship, and pleasing the human eye. Breed standard is an official description of a breed. Canine is word for dog or doglike. Dog is an adult male canine. Litter is a group of puppies' boom at one time to one female. Tail chasing is a normal form of play for puppies. Digging is an instinctive activity that dogs retain from their wild ancestors. Panting helps a dog stay cool. No one knows for sure when the dog became man's best friend. But for thousands of years humans have bred dogs for certain qualities, such as good tracking skills or guarding abilities or for small size and companionship.