The pit bull's ancestor, the bulldog, was bred for a variety of work, including farming, hunting, protection, and companionship. Bulldogs and their offspring were also bred for bull and bear baiting and pit fighting (fighting against other dogs). Such dogs were required to be loyal, human-friendly, intelligent, hard working, and persistent. Many of these qualities still remain in modern pit bulldogs.
Today's pit bulls are somewhat different from the original working bulldogs. In today's society we rarely need farming and hunting dogs, and pit fighting, bull baiting, and other cruel bloodsports are, thankfully, outlawed. Today, pit bulls are less of a working dog than a household companion and guardian. Some pit bulls find work in the agility field, in weight pulling competitions, on a search-and-rescue team, or as a therapy dog at a nursing home.
There are today three very different breeders trying to create three very different types of pit bulls. In addition, many pit bulls are crossed with other breeds, like mastiffs or retrievers, and acquire some of the characteristics of these breeds. This means that the pit bull's physical and mental characteristics vary widely among different strains, and it makes it almost impossible for me to describe an average pit bulldog to you.
The first kind of breeder is the show breeder. These breeders, like all other show breeders, are concerned primarily with a "breed standard" created by the various dog organizations. They breed for stable temperament and physical conformation to that standard. These dogs are registered with one of the national dog associations. These pit bulls are generally attractive and friendly, and usually pet quality - but they can be expensive.
Another kind of breeder is the pit fighter. The pit fighter engages in the inhumane activity of dog fighting. Pit fighters breed for aggression. In the novice fighting world, it is generally believed that the more aggressive the dog, the better it will fight. Thus, those who breed pit bulls with intent to fight them often mistakenly breed and "train" (read "abuse") for human-aggression as well. Some pit fighters, especially more experienced fighters who fight under a tried-and-true set of rules and regulations, understand that their pit bulls must be human-friendly. This is because dog fighters must be able to handle their dog in the midst of a heated dog fight, and they are also expected to bathe the opponent's dog before the fight. Human-aggressive dogs are not acceptable under such rules. However, in either case, this kind of pit bull is bred and trained for endurance to pain, gameness (willingness to persist), and viciousness. This is the kind of pit bull you hear about constantly in the media, and these owners and breeders are primarily responsible for the breed's onerous reputation. These dogs are NOT representative of the breed. They are a minority.
The last variant of the breed is the mixed, "mutt", or pet pit bull. These dogs are usually the result of accidental breeding, puppy mills, and, in some cases, hobbyists who enjoy breeding pit bulls. You most often find this kind of dog at the animal shelter, a foster home, a rescue group, or in the newspaper. These pit bulls are not registered and their genetics/bloodline is questionable. They are often only part pit bull, usually mixed with another breed such as mastiff, Labrador Retriever, Chow Chow, or any of a number of dogs.
I am assuming you're wondering what kind of pet a pit bull can be. As a result, I am not considering the dogs bred for fighting. Also, please keep in mind that all of the information below is variable according to the dog, and that each and every dog is different, so you should not assume that all of this will hold true for any single APBT. Keep in mind that pet-quality pit bulls are usually not purebred, which means you never really know what you're going to end up with. Remember - even a "registered" or "papered" dog is not necessarily a perfect representative of the breed! It only means that the dog's parents were registered. It does not mean that the dog meets the breed standard, is of good temperament or health, or is a good-quality pet.
The pit bull is a medium-sized dog with broad shoulders and
powerful muscles. There are two general kinds of pit bulls. The
first are the larger, "gamey" pit bulls of which most are American
Pit Bull Terriers, and are taller and more slender. The second are
more compact pit bulls, often the American Staffordshire Terriers,
which tend to be shorter, thicker, with blockier heads and stubbier
Pit bulls are energetic, playful, loyal, loving, protective, and intelligent. As pets, they are unlike any other breed of dog. When properly raised, socialized, and obedience trained, the pit bull makes an ideal dog for couch-lovers and outdoor enthusiasts alike. However, it should be noted that this is NOT a good breed for a beginning dog owner, a careless/lazy owner, or a child. My reason is this: As with any breed, if you do not know what you are doing (i.e. you are clueless about owning a dog), you may end up with an out-of-control dog. However, for a pit bull to become an out-of-control dog is dangerous for the dog, its owner and family, its neighbors, and the breed in general. Like any large, powerful dog, a pit bull can do damage if it is allowed/taught to be dominant or aggressive. In addition, an uncontrollable pit bull is another black mark on the breed's already damaged reputation. If pit bull owners want their dogs to enjoy the same freedoms that other breeds enjoy (in other words, prevent breed-specific legislation), they MUST understand the issues facing pit bulls and their owners, understand how to train and control a dog, and go above and beyond the responsibilities of ordinary dog owners!
With pit bulls, early training and socialization are key to a well behaved dog. Owners should not leave this dog to spend its life bored and alone in a backyard. This dog must be a close and beloved pet, and owners should devote much time and attention to it. In addition, owners must not indulge any tendency to dominate, but must control the dog at all times with consistency and fairness. I do not recommend a pit bull puppy, or for that matter any dog, as a companion for a young child because the child will not have the knowledge, consistency or discipline needed to train the dog and lacks the strength necessary to handle an untrained pit bull. If you are looking for a good pet for a child, get a fish or a small lizard.
Alone in the yard, pit bulls do not typically dig despite their "terrier" name (they are not actually terriers). However, they can jump fences if given a reason, and weak, rotten, or broken fences are not sufficient to keep a pit bull contained. Most pit bulls will not attempt to leave the yard unless they are given a really, really good reason - provided they are not bored, ignored, or neglected. To ensure your dog's safety, I recommend keeping a pit bull in a locked kennel when you are not home. Bored pit bulls can hurt themselves, and pit bulls have been known to be stolen right out of their backyards by people who want to fight them.
Alone and loose in the home, the pit bull can do significantly more damage. A bored pit bull will find something to chew and shake, and that something might be your sofa pillows. Though you think the dog knows which things are toys and which are not, when you are not home, this may not be so clear to the dog. Again, it is best to keep the dog in a secure kennel when you are not home, to ensure that the dog does not damage something valuable.
Come to think of it, these guidelines are pretty much the same as with any other breed.
A human-aggressive pit bull is probably an abused or otherwise improperly raised dog. Some illicit APBT breeders produce human-aggressive pit bulls because they are ignorant morons who have fallen for an erroneous stereotype. Some people would have you believe that pit bulls make good attack or guard dogs. This is absolutely not true, and attempting to make a pit bull into an attack dog is an abusive and dangerous thing to do. It will absolutely ruin the dog. Some pit bulls have been bred or raised to be excessively protective of the home. I consider these dogs to be extremely dangerous, and I do not think they are pet quality. There is too much potential for an accident to occur with a dog that is trained to attack a strange person (mailman, meter reader, electric/phone service, Girl Scout, UPS guy, neighborhood children whose ball landed in your backyard - think about it).
Dog-dog aggression is seen in individual dogs across all breeds and in varying levels of severity. Its causes are many and frequently disputed by experts. Some believe that dog aggression is purely genetic, others that it is primarily environmental (behavioral), and still others that it is a combination of the two.
One of the biggest mistakes a person can make is to assume that all pit bulls are dog-aggressive because they have a recent history of being bred to fight other dogs. You can not simply say, "All pit bulls are dog-aggressive" because it's not true. It is very much an individual trait that varies from dog to dog. So - many people end up with a dog-aggressive pit bull and say, "Well, that's just the way pit bulls are." This is a damaging statement to make for many reasons. Firstly, it is not true. There are plenty of pit bulls out there that are perfectly social and friendly with other dogs. Secondly, it is a totally self-defeating statement that effectively eliminates all possible solutions. It would be better to say, "My dog is acting dog-aggressive." This leaves open the door for improvement (via training, socializing) because you are not immediately assuming that the aggression is an unchangeable trait.
That being said, I think it is important for me to point out that dog-dog aggression does appear in pit bulls with some frequency - in part because of their genetics and in part because of their training. So owners should always be aware of their dog's state of mind when it is around other dogs. And if your pit bull has a tendency to act aggressively towards other dogs - be responsible! Don't bring your dog to places where there might be an off-leash dog. Don't let your dog off the leash around other dogs. And get help from a professional behaviorist - the aggression might be stemming from other factors in your dog's life, not necessarily genetics. Never ignore aggressive behavior, and never try to "fix" it yourself - you could make it worse.
Do not confuse dog-dog and dog-animal aggression for dog-human aggression!! Dogs can and do make the distinction between people and other animals very clearly. Just because a dog is aggressive towards other dogs does not mean that it will also act aggressively toward people.