A set of
theories regarding how entities
learn.
Pavlov and the
behaviorist really hammered out the basics here, although there's a lot more to it that. The basics are associative conditioning, including
positive reinforcement,
positive punishment,
negative reinforcement, and
negative punishment, and
classical conditioning.
Positive always means the application of some stimulus, and negative always means the removal of some stimulus. Reinforcement always means trying to make the behavior more likely, and punishment always means trying to make the behavior less likely.