I like most of animals as long as they are not harmful or dangerous, but my favorite one is dog. Dogs are well known for their intelligence and loyalty; and in my opinion, their looks are also very cute. There are many different breeds in the world, and most countries have at least one featuring dog breed of their own. Nowadays, most breeds of dog are not the same as they were from hundred years ago, but they have been artificially selected for particular appearances and behaviors by people for specific purposes. Because of this selective breeding, dogs have developed into hundreds of varied breeds, and they show more connection with people than any other land mammal. Some of the most popular breeds are Golden Retriever, Siberian Husky, Alaska, Bulldog, Doberman, German Shepherd, and it can be said that each breed has their own significant function in human’s life. Dogs have been the best companions for human at a very early age, their roles in hunting, herding, pulling loads and protection truly helped human in a lot of aspects. More recently, they have developed more practical roles in assisting police and military, companionship, and helping handicapped ones, and most people accept that dogs appear in their lives more than they had ever thought. My family has a little dog, and he has all of the best qualities of a good one. He is actually my best friend since I am the one who spends most time playing with him. I love him very much, but I have to accept a fact that his life span is much shorter than human. A well – treated dog can live up to 12 or 15 years, and each year in dog’s life span is equal with 5 years in human’s one. Since dogs are the most popular animal to show such love and loyalty to human, its shortage in life span is truly a sad thing for all the dog lovers. Although I do not have much time with my beloved dogs, I always love them as my best companions in life.