Clickers are small noise devices that were sold years ago as toys to make a cricket-like noise.
When the clicker is pressed it makes a sharp, distinct sound. Scientists have used this 'click' to pinpoint the exact moment a desired action occurs after which a reward is offered. That reward can be treats, a toy, or praise.
When used to teach animals, we first pair the click with a reward. When the animal performs the action we seek, we click to let him know that behavior was what we wanted and that a reward is coming. Amazingly, after a short time the animal will begin to do several behaviors in an effort to 'get the click'.
Clicker training is effectively used with dogs, cats, horses, chickens, rats and many other species of animals. It can be used to teach behaviors, calm an animal, inspire confidence and more.
Absolutely not. Although the use of a clicker is a positive reinforcement method which as been scientifically-proven to successfully train a dog and retain desired behaviors, it is but one way of teaching your dog. Somtimes we use a 'marker word'.
In addition, there are certain applications where, rather than using a clicker or marker of some kind we offer 'life' rewards. An example of this would be when your dog sits and stays until the door is opened. The reward for that sit/stay would be being 'released' to go outside.
Marking an action with a distinct sound that is paired with reward is not a new concept. Trainers of dolphins, killer whales, etc. have been using this method of behavior modification for decades, only instead of a clicker and treat they use a whistle and a fish. Clickers are used to help train gymnasts and dancers, to teach people with some learning disabilities (called TagTeach), as well as other applications where body position is learned through muscle memory.