Positive reinforcement is a fundamental concept in behaviorism. It refers to the process of increasing the likelihood of a behavior recurring by adding a desirable stimulus immediately after the behavior occurs. 

Positive reinforcement involves presenting a rewarding stimulus (positive) to strengthen or increase the frequency of a desired behavior (reinforcement). For example, within a family dynamic or at school, one can give a child a sticker for completing their homework.This is positive reinforcement because it encourages them to continue doing their homework in the future.

Positive reinforcement is a key component of operant conditioning, in which behaviors are strengthened or weakened based on the consequences that follow them. According to behaviorism, individuals learn through their interactions with the environment, and positive reinforcement is one way to shape behavior by associating it with positive outcomes.

Positive reinforcement can also be used in behavior modification to encourage desired behaviors and discourage undesired ones. By providing positive consequences for desired behaviors, individuals are motivated to repeat those behaviors in the future.