This document discusses the economic concept of utility. It defines utility as the satisfaction derived from consuming goods and services, and can be measured either cardinally or ordinally. Total utility is the satisfaction from consuming multiple units, while marginal utility is the change in total utility from an additional unit. The law of diminishing marginal utility states that as consumption increases, the satisfaction from each additional unit decreases. This is illustrated with an example showing the total and marginal utility derived from consuming successive ice creams diminishing after the first few. Exceptions to the law and its assumptions are also outlined.