Dogs have been selectively bred for thousands of years, sometimes by inbreeding dogs from the same ancestral lines, sometimes by mixing dogs from very different lines. The process continues today, resulting in a widening in appearance without speciation, "from the Chihuahua to the Great Dane."
Dog breeds are typically divided into a few basic categories: companion dogs, guard dogs, hunting dogs, herding dogs and working dogs. The top dog breeds for every purpose are represented here. Despite the names, in contemporary America, most breeds - even hunting or herding dogs - service as companies for individuals and families.
All puppies are cute, but some breeds have that extra “je ne sais quoi” that makes them irresistible. For this reason, some of these breeds are popular in greeting cards, commercials and other marketing materials.
Some breeds have so much energy and are so active that if you do not give them a sufficient workout every day - a long walk and hard run - their pent up energy will quite likely manifest itself in destructive behavior.