Dogs have been domesticated the longest of any animal. They have many different jobs all over the world, such as: herding, guarding, pulling sleds or carts and rescuing people. Dogs are used for many things that people need help with. There are seeing-eye dogs for the blind and therapy dogs for people that have special needs. Dogs come in more shapes and sizes than any other mammal, from the teacup chihuahua to the great dane.
Dogs really are "man's best friend". They are the only animal besides humans that have an innate ability to understand pointing and eye motions. This makes training them very easy compared to many other animals. They are also very social, many people keep them as companions.