Dog training requires a basic understanding of what reinforcements and punishments are and how they work. Your dog being the learner is the only one that can decide what is rewarding to them, as well as what is aversive to them. The most basic definition of Punishment is something that lessens the likelihood of a behavior from happening.
Behaviors that produce an effect that is desirable are ones that a dog is more likely to repeat, whereas behaviors that produce an undesirable effect are ones that are less likely to be repeated. He gave us our entire foundation for trial and error training, which helped us to focus on problem-solving skills during training.