Negative reinforcement is the removal of an unpleasant stimulus upon recognition of the desired response.
In operant conditioning the focus is to reinforce behaviors we want and eliminate behaviors we do not want. Positive reinforcement means providing a pleasant stimulus when we see the behavior we want, like giving a dog a bone after he sits when we tell him to.
Negative reinforcement is not the opposite of positive reinforcement, and it is not punishment. Punishment is providing a negative stimulus as a result of the behavior we do not want, such as yelling “bad dog!” when he pees on the carpet.
Negative reinforcement is providing the negative stimulus until you get what you want. An example of this would be locking a dog up until he does something you want him to. The locking up is the negative stimulus, because the dog does not like it. If you want him to lie down, you would let him out once he did it.