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."
Dogs with short coats require virtually no grooming, just a brush and wipe down every so often. Pet dogs with long coats require either regular clipping every eight weeks or so (where their coats are clipped short) or there long coats need to be brushed practically every day. Show dogs, or dogs with long coats, require daily brushing or else there coat will become matted and tangled. Not only can it hurt your dog if he has tangled and matted hair, but it will also become dirty and he will look shaggy and ugly if you do not regularly brush his coat.
Getting a dog is not just an emotional commitment; it is also a financial one, too. But when it comes to money, not all dogs are created equal. A bit of research goes a long way in discovering which dog breed is best for your budget.
Some dogs will patiently put up with little children who pull their ears or accidentally poke them in the eyes, while others will not and map nip or bite back in defense. So if you want a dog who is excellent with children avoid breeds which may have a dominance streak or that have short tempers.