Fundamentally, dog training is about communication. From the human perspective the handler is communicating to the dog what behaviors are correct, desired, or preferred in what circumstances. From the canine perspective the handler must communicate what behaviors will give the dog the most satisfaction to his natural instincts and emotions. Without that inner satisfaction a dog will not work well.
A successful handler must also understand the communication that the dog sends to the handler. The dog can signal that he is unsure, confused, nervous, happy, excited, and so on. The emotional state of the dog is an important consideration in directing the training, as a dog that is stressed or distracted will not learn efficiently.
According to Learning Theory there are a four important messages that the handler can send the dog:
Reward or release marker
Correct behavior. You have earned a reward. For example, “Free” followed by a reward.
Bridge
Correct behavior. Continue and you will earn a reward. For example, “Good”.
No reward marker
Incorrect behavior. Try something else. For example, “Uh-uh”...