Operant conditioning (or instrumental conditioning) is a form of learning in which an individual's behavior is modified by its consequences; the behavior may change in form, frequency, or strength. Operant conditioning is distinguished from classical conditioning (or respondent conditioning) in that operant conditioning deals with the modification of "voluntary behavior" or operant behavior. Operant behavior operates on the environment and is maintained by its consequences, while classical conditioning deals with the conditioning of reflexive (reflex) behaviors which are elicited by antecedent conditions. Behaviors conditioned via a classical conditioning procedure are not maintained by consequences.

Reinforcement and punishment, the core tools of operant conditioning, are either positive (delivered following a response), or negative (withdrawn following a response). This creates a total of four basic consequences, with the addition of a fifth procedure known as extinction (i.e. no change in consequences following a response).