Operant behavior is a type of learning process where behaviors are modified through the association of stimuli with reinforcement or punishment. It is also known as instrumental conditioning, and it is a method of learning that uses rewards and punishment to modify behavior. In operant behavior, stimuli can be appetitive or aversive, and responses to such stimuli can either be positive or negative reinforcement. Positive and negative reinforcement do not mean good or bad, but rather refer to the addition or removal of a stimulus to increase the likelihood of a behavior occurring again.

Operant behavior is said to be "emitted," meaning that it is not elicited by any particular stimulus. Instead, the behavior of an individual varies from moment to moment, in such aspects as the specific motions involved, the amount of force applied, or the timing of the response. Most behavior cannot easily be described in terms of individual responses reinforced one by one, and the scope of operant analysis is expanded through the idea of behavioral chains, which are sequences of responses bound together by the three-term contingencies defined above.

Operant conditioning was first described by behaviorist B.F. Skinner, who believed that the cause of human behavior is something in a person’s environment, and the consequences of a behavior determine the possibility of it being repeated. Behavior that is followed by a pleasant consequence is likely to be repeated, and behavior followed by an unpleasant consequence is less likely to be repeated. Punishment is defined as any change to the surrounding environment that reduces the probability of a behavior occurring again.

In summary, operant behavior is a type of learning process where behaviors are modified through the association of stimuli with reinforcement or punishment. It is a method of learning that uses rewards and punishment to modify behavior, and it is said to be "emitted."