A form of learning where a subject is rewarded for desired behavior by the removal of a negative, such as pain, hunger, or a distressing noise. This term is often confused with punishment, which is the introduction of a negative (the punishment) to discourage behavior.
Negative Reinforcement is the removal of something bad. Punishment is the introduction of something bad.
Negative Reinforcement: "Good behavior" in the prison system, where the negative (prison time) is reduced as a reward for not causing problems.
In comparison, the original prison sentence itself is punishment - a negative introduced to discourage behavior.