Operant behavior are actions that operate on the environment or are controllable by an individual. These are set with the two different types of learning within psychology: classical conditioning and operant conditioning. Of course, operant behavior lies within the latter.
Operant behavior is often a voluntary action a subject can or must take. Our bellies rumble when we’re hungry and can smell a sweet delicious peanut butter tuna sandwich nearby. That’s an example of classical conditioning. But the trained action of reaching out to steal someone else’s delicious peanut butter tuna sandwich, an action we’ve learned is always successful in the past, is an operant behavior.