Final answer:
Marginal utility is the additional satisfaction that a consumer derives from consuming one additional unit of a good. It diminishes as additional units are consumed, following the law of diminishing marginal utility.
Step-by-step explanation:
Marginal utility is the additional satisfaction that a consumer derives from consuming one additional unit of a good. It is the change in total utility divided by the change in quantity consumed. Marginal utility diminishes as additional units are consumed, meaning that each subsequent unit of a good consumed provides less additional utility. This is known as the law of diminishing marginal utility.