The dog is a domesticated subspecies of the gray wolf, a mammal of the Canidae family of the order Carnivora. The term encompasses both feral and pet varieties and is also sometimes used to describe wild canids of other subspecies or species. The domestic dog has been one of the most widely kept working and companion animals in human history, as well as being a food source in some cultures. There are estimated to be 400 million dogs in the world. People always say: ?dogs are people?s best friends?. They usually follow you wherever you go, shake their tails when they see you back from work. Dogs are lovely and cute. You are training your dog, you hope it could races with other strong dogs, so you set some barriers for him and not forget give him some bones for rewards. Let?s see how your dog goes.