Marginal utility theory in economics

Marginal utility theory explains how consumers decide to buy more or less of a good based on the additional satisfaction they get from each extra unit. As you consume more of a product, the extra satisfaction usually decreases—this is called diminishing marginal utility. For example, the first slice of pizza may bring great enjoyment, but by the fourth or fifth slice, the additional pleasure declines. Consumers make choices to maximize their overall happiness by weighing the utility gained from each extra unit against its cost, leading to optimal purchasing decisions.