This document discusses concepts related to consumer equilibrium and demand. It defines key terms like utility, marginal utility, total utility, and how they are related. The law of diminishing marginal utility and how it impacts demand is explained. Two approaches to modeling consumer equilibrium are presented: the utility approach and indifference curve approach. Consumer equilibrium conditions and assumptions are outlined for both single and multiple goods. Factors that determine demand, the law of demand, and exceptions are also summarized. Elasticity of demand and its measurement are briefly introduced.