Dogs are probably the most popular pets in the world. The relationship between humans and dogs is well-known. Dogs were one of the first animals domesticated by humans thousands of years ago, even before sheep and cattle. Today, there are about 400 million dogs in the world. Art, literature, and history speak about the relationships between people and dogs. It is not surprising that a dog makes the most loyal and affectionate pet and is called a man's best friend. Any dog lover can say that a dog brings a smile to its owner's face every time they look at them. Dogs motivate people to spend more time outdoors. They are also friendly towards children. Some dogs can even look after kids and protect them if necessary. If you get a dog, you get a true friend for a lifetime.