Dog clicker training uses the same techniques used with training dolphins and sea mammals. The dolphins learn that the sound of a whistle means a food or toy reward. In the same way, a dog associates the sound of a click with a reward. Small, plastic clickers are used instead of words because the click sound is consistent.
The first dog trainer to popularize clicker training in dogs was former dolphin trainer Karen Pryor, in her book "Don't Shoot the Dog! The New Art of Teaching and Training" (1999).
Initially, treats used are small, cubed low calorie food treats, although commercial training treats are now made. As the dog progresses in training, favourite toys can be used as rewards.
Getting the dog to understand that click equals a treat is called "priming." This is simply clicking and then immediately giving a dog a treat until the dog looks expectantly for a treat at the sound of a click.
When the dog learns to associate the sound of the click with a treat, the trainer introduces a simple trick that the dog already knows. The trainer says the command and, when the dog performs, he clicks and gives the dog a treat.
Breaking a trick or behavior down into steps and clicking and rewarding the dog for doing each step is called "shaping."
- Image from Wikimedia Comons.