The content of the law of diminishing marginal utility in economics is: within a certain period of time, under the condition that the consumption of other commodities remains unchanged, as consumers increase their consumption of a certain commodity, The incremental utility that consumers get from each successive unit of consumption of the commodity, that is, the marginal utility, is diminishing.

The law of diminishing marginal benefit is that within a certain period of time, when other conditions remain unchanged, when consumption begins to increase, marginal utility will increase, that is, the total utility increases greatly, but it accumulates to a considerable amount of consumption After that, as the consumption increases, the marginal utility will gradually decrease; if the marginal utility is still positive, it means that the total utility continues to increase, but the increase will gradually level off; when the consumption accumulates to saturation and the marginal utility decreases to 0, it means that the total utility will not If the marginal utility decreases and becomes negative, the total utility will gradually decrease. The law of diminishing marginal returns reflects the inverse relationship between production factors and returns.

The law of diminishing marginal utility (also known as the law of diminishing marginal utility, diminishing marginal contribution), diminishing marginal utility is a basic concept of economics, which refers to the situation in which resources are used as inputs. For an enterprise, the utility of unit resource input on product output is constantly decreasing. In other words, although its total output is increasing, its second-order derivative is negative, making its growth rate continue to slow down, making its Eventually it will reach a peak and may decline, that is, the marginal product of variable factors will decrease. When a consumer consumes more and more of a certain item, the utility (i.e., marginal utility) gained from the consumption of the last newly added unit of the item usually becomes less and less (decreasing), which is called marginal utility. The law of diminishing utility. Also called Gerson's first law.

The popular saying of the principle of diminishing marginal utility is: at the beginning, the benefit value is very high, and later on, the benefit value becomes smaller. Expressed in mathematical language: x is the independent variable, y is the dependent variable, y changes with the change of x. As the value of x increases, the value of y also increases, but the magnitude of the increase continues to decrease. This is the famous principle of diminishing marginal utility.