In the twentieth century, formalized dog training originated in military and police applications, and the methods used largely reflected the military approach to training humans. In the middle and late part of the century, however, more research into operant conditioning and positive reinforcement occurred as wild animal shows became more popular. Aquatic mammal trainers used clickers (a small box that makes a loud click when pushed on) to "mark" desired behavior, giving food as a reward. The change in training methods spread gradually into the world of dog training. Today many dog trainers rely heavily on positive reinforcement to teach new behaviors.
Head halters are an alternative to collars that works similarly to a horse halter. The halter fits over the dog's snout and behind its head (leading it to sometimes be mistaken for a muzzle). Halters reduce the dog's ability to successfully pull on the leash, but do not eliminate it. If the halter is used with a sharp jerk on the leash, neck injury to the dog may result, but used correctly head halters have not been shown to cause harm.
Unless you plan to keep your dog outdoors--and few of us do because it's not recommended--you'll need to teach your dog where to eliminate. Therefore, house training (also called housebreaking or potty training) is one of the first things you need to work on with your dog. Crate training can be a very helpful part of the training process. This includes house training as well as many other areas of training: