What is Reward System?

Legal Definition
The reward system is a group of neural structures responsible for incentive salience (i.e., "wanting", desire, or craving), pleasure (i.e., hedonic "liking"), and reinforcement learning (e.g., positive reinforcement). Reward is the attractive and motivational property of a stimulus that induces appetitive behavior – also known as approach behavior – and consummatory behavior. In its description of a rewarding stimulus (i.e., "a reward"), a review on reward neuroscience noted, "any stimulus, object, event, activity, or situation that has the potential to make us approach and consume it is by definition a reward." In operant conditioning, rewarding stimuli function as positive reinforcers; the converse statement is also true: positive reinforcers are rewarding.

Primary rewards are those necessary for the survival of one's self and offspring, and include homeostatic (e.g., palatable food) and reproductive (e.g., sexual contact and parental investment) rewards. Intrinsic rewards are unconditioned rewards that are attractive and motivate behavior because they are inherently pleasurable. Extrinsic rewards (e.g., money) are conditioned rewards that are attractive and motivate behavior, but are not inherently pleasurable. Extrinsic rewards derive their motivational value as a result of a learned association (i.e., conditioning) with intrinsic rewards. Extrinsic rewards may also elicit pleasure (e.g., from winning a lot of money in a lottery) after being classically conditioned with intrinsic rewards.
-- Wikipedia
Legal Definition
The allocation of compensation and benefits to employees that follow the standards, rules and procedures established.