The German Shepherd Dog, or Deutscher Schaeferhund is the most widely distributed and best known of the Continental Shepherds. The GSD has been called an Alsatian by some people, however, this is not the "correct" terminology -- an Alsatian is a person.
The FCI (or International Kennel Club Federation - for those of us who speak English) recognizes breeds by their name in the country of origin, in this case Germany and Deutscher Schaeferhund.
According to FCI standards there is a long and short haired variety of GSD. The KC defers to the FCI standard; the AKC and CKC do not mention hair length, however, in practice only short haired varieties are shown in bench trials.
The one thing all standards are in complete agreement on -- there is a huge variety of 'looks' amongst individual members of the GSD breed.
Colors are typically variations on tan, red, or gray, and black. Darker richer colors are preferred -- white is a disqualification.
Over time, the adult white GSD proved to be stable enough (there were concerns that the solid white color would prove to be a marker of an unstable personality, or horrible health problems) that more reputable breeders became involved with keeping these progeny; there is now a movement to have them recognized as a separate breed - some breeders call them the American White Shepherd, others the White German Shepherd.
I'm sure we'll see ongoing developments in the years to come. I've known, trained, and lived with a number of GSD, including white, and honestly the range of personalities is the same, regardless of the colors.
There are also all black GSD and again, while you will not find them showing up in bench shows, they have their own faithful followers also. Far more important than the dogs color, is the personality. It used to be argued that the single colored dogs, particularly white, were "off" and were more likely to have off personalities. Not so much.
The only thing I have personally noted about the single colored GSD is that they are more likely to have slightly more noticeable confirmation faults -- which in no way affects their personalities. A lot of GSD have confirmation faults; like Labradors it is sometimes a real chore to find a GSD that doesn't have noticeable confirmation faults.
increased the likelihood of hip and joint problems, which even as breeders are trying to correct from this exaggeration, continue to plague the breed. Years ago I traveled some distance with my sister to help her evaluate an 18 month old GSD she was considering buying from a very reputable breeder.
As the breeder ran the dog around us in a circle I pointed out that he was ever so slightly starting to favor his right front leg as he ran - a barely noticeable skip. She called us that night after taking the dog to the vet - the dog had already been put down - he was just showing the first signs of complete joint destruction in ALL his legs.
Some people have found the best way to increase the likelihood of getting a healthier GSD for a pet home, is to look for the dogs bred from working lines. The exaggerated back end was never popular in working lines and these lines of GSD kept a stronger back line.
There are some very valid reasons that the GSD is considered one of the most versatile dogs in the world. Intelligent, trainable, eager to please their people, flexible; unlike some 'guard' breeds, a properly trained and temperamented GSD can be turned on and off like a switch, moving immediately from socializing with children, to running down a criminal, and then back to calmly walking through a crowd on crowd control duty.
Unfortunately, lack of training or an incorrect temperament can also get in the way of this ideal behavior. I have witnessed proper GSD and handlers do exactly the kind of thing I'm describing.
I have witnessed improperly trained handlers and GSD get revved up and then stay "up" when handlers hadn't been trained that they and their dogs had to practice coming straight back "down" (a skill actually harder for the handler than the GSD to put into practice.)
I could actually go on for a lot longer about the GSD... instead I will just share some final pictures of the GSD in some of the many roles they fill for humans.