Basics: Dogs are generally valued for their intelligence. This intelligence is expressed differently with different breeds and individuals. For example, Border Collies are noted for their ability to learn commands, while other breeds may not be so motivated towards obedience, but instead show their cleverness other ways such as stealing food or escaping from a yard.

Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Within the range of extremes, dogs generally share attributes with their wild ancestors, the wolves. Dogs are predators and scavengers, possessing sharp teeth and strong jaws for attacking, holding, and tearing their food. Like many other predatory mammals, the dog has powerful muscles, fused wrist bones, a cardiovascular system that supports both sprinting and endurance, and teeth for catching and tearing. Compared to the bone structure of the human foot, dogs technically walk on their toes.

Cool Facts: If you look at your dog while it's sleeping, sometimes you'll see its eyes move and twitch under its eyelids. Humans do this too, and we definitely dream. So researchers are almost positive that dogs have dreams too. But guess what? No one knows what dogs dream about.

The smartest dogs are said to be the Border Collies, Poodles and Golden Retrievers.

Bulldogs were originally bred to bait and fight bulls and bears.

As Pets: The dog is one of the most popular pets in the world. It ordinarily remains loyal to a considerate master, which is why it holds the title as 'man's best friend.' A dog fits easily into family life.