What is classical conditioning and who discovered it?

Classical conditioning is a form of learning where a neutral stimulus becomes associated with a stimulus that naturally produces a response, so that the neutral stimulus alone eventually triggers the response. Ivan Pavlov discovered it while studying digestion in dogs. He noticed that dogs began salivating at the sight of the lab assistant who brought food, not just at the food itself. By repeatedly pairing a bell with food, the bell alone eventually caused salivation.