Marginal utility
Marginal utility is a term used in economics. The marginal utility of a commodity refers to the increase in utility that a person or group gets this property by an additional unit. Thus, the marginal benefit is the differential of the utility function.
Diminishing marginal utility
When delivery is usually a decreasing marginal utility. Consumed a person after a first good G1 G2 another good, the benefit decreases this good G. For example, taking the marginal utility of rolls above a certain amount from increasing. A person may consume a roll in a given time. From a certain amount of rolls of benefit decreases each other bun. 10 rolls do not have the 10-fold benefit as a roll and 100 roll not the hundred-fold. The same applies to the financial income. Although a person can spend about a monthly income of 1000 euros in a given time. However, the benefit of additional revenue does not increase proportionally into randomness. An income of 100,000 euros a month does not have the 100-fold benefit for the same person, as many needs have been satisfied.
Example
Someone at the fair hunger and therefore buys a bratwurst. This hunger is at least partially breastfed. Did he then still hungry, he buys another one that probably still taste him. By the fourth or fifth sausage he can quench any further hunger, and he eats then the seventh or eighth is, even be bad to him. The added benefit of the eighth Bratwurst ( = their marginal utility ) is therefore negative. Better it would have been, he would have instead bought eg a glass of apple juice.
Marginal utility and happiness
The marginal utility determines the satisfaction or happiness of people. The satisfaction of people is increasing with increasing income, although the boundary growth decreases, that is, satisfaction increases relative to incomes rise at a decreasing rate. Accordingly, the increase of $ 20,000 annual income over $ 10,000 is significantly stronger than that of 90,000 to 100,000 or from 100,000 to 200,000.