what is marginal utility

Marginal utility is a concept in economics that describes the change in utility (satisfaction or pleasure) from consuming one additional unit of a good or service. It can be positive, negative, or zero. Positive marginal utility occurs when the consumption of an additional unit increases total utility, while negative marginal utility occurs when the consumption of one more unit decreases the overall utility. The law of diminishing marginal utility states that as consumption increases, the additional satisfaction or utility gained from each additional unit consumed falls, leading to a continuing reduction in satisfaction for greater amounts. Economists use marginal utility to determine the optimal quantity of a good or service that a consumer is willing to purchase