For thousands of years now, dogs have been selectively bred to produce varieties with characteristics superior to their predecessors. At first, the breeding focused on the dog's use, for example its hunting ability. This resulted in a vast diversity of dog breeds. But it did not stop there, later dogs were bred for more distinct and attractive forms.

A variety of dogs can be called a breed (distinct kind of family) on the condition that its parents have offspring of the same characteristics (e.g. behavior and characteristics). This is called true breeding.

Generally speaking, the majority of traditional breeds are termed "purebreds". Domestic dogs in general are called Canis familiaries.

The following are the different classifications of dog breeds:

* Bulldogs

* Extinct dog breeds

* Cur

* Fighting dogs

* Gun dogs, including Pointers, Retrievers, and Spaniels

* Herding, including Sheepdogs

* Hounds, including Sight hounds and Scent hounds

* Sled dog

* Hunting

* Toy

* Terrier

* Working (or Utility)

However, these can be further classified into smaller but similar dog breeds, such as the Lurchers, Mastiff types, Pitbulls and Spitz types.

The herding breed is most commonly known as the sheepdogs. They have the ability to control the behavior (specifically the movements) of other animals. These are usually an intelligent type of dogs and are devoted to their owners, whom they consider partners, for they normally use their own judgement as well as their owner's commands. Most forms of this breed have the tendency to drive and to gather the herd.

The examples of the herding type are Puli, Briard, German Shepherd, Collie, and Old English Sheep dog.

The oldest dog breeds is the hounds. They are differentiated into two categories:

* Sight hounds -- which hunt by sight and include the greyhound build.

* Scent hounds -- which hunt by scent and include the foxhound build.

* Some breeds have the combination of both and some don't look like hound dogs at all.

The examples of which are the Basenji, Basset hound, English Foxhound, Saluki and the Beagle.

On the other hand, are the non-sporting dogs, also known as the companion dog breeds. This is the most diverse of all dog breeds and is sometimes considered the catchall for dog types that cannot be categorized elsewhere. The following are the examples of this dog breed: Bulldog, Boston terrier, Dalmatian, Chinese Shar-pei, French Bulldog, Standard and Miniature Poodle, and Tibetan Terrier.

The sporting breed are the modern hunters. In general, they work with hunters to complement the hunter's abilities. Setting and pointing breeds work by locating game for the hunter. Spaniels are known for flushing out the game so the hunter may shoot the prey. The retrievers bring the game back to the hunter. Examples of this type are the Labrador Retriever, Golden Retriever, Chesapeake Bay Retrievers, English Setter, Field Spaniel, Pointer and the Sussex Spaniel.

The terrier group includes the dogs that hunt for rodents and other vermin found near the ground. The term terrier actually originated with the word "terra," which means earth. Some were later bred to fight against one another. Vermin-catching terriers are further classified into two types: the long-legged and the short-legged.

Examples of this dog breed are the Irish Terrier, Bull Terrier, Lakeland Terrier, and the Miniature Bull Terrier.

The toy dogs are usually comprised of the miniature version of the other groups of dogs. However, quite a number of these types are ancient in origin, which makes it difficult to trace them with other dog varieties. This group includes: Chihuahua, Papillion, Japanese Chin, Poodle, Pug, and the Toy Fox Terrier.

The working dogs on the other hand are known for their intelligence and hardiness. They are sub-divided into:

* Sledding breeds

* Protecting or guarding breeds

* Rescue breeds

* Carting breeds

Examples of this dog breed are the Boxer, Alaskan Malamute, Bull mastiff, Great Dane, Doberman, Newfoundland, and Rottweiler.