A concise introduction to the marginal-utility approach to value presents a systematic analysis distinguishing utility from exchange value, explains how individual subjective valuations produce a scale of value and marginal utility, and treats complementary goods and difficulties of application. It develops how subjective valuations become the basis of prices, traces connections between marginal products, costs of production, and product valuation, and offers clarifications and lecture-style appendices that emphasize the demand-side perspective for students learning the central principles of value theory.