Consumer choice is what derives demand Consumer choice is what derives demand. Utility theory is a basis for understanding consumer choice.
Utility is a measure of satisfaction.
Total Utility is the total satisfaction a consumer derives from consumption. Utility is subjective. It is not the same to all people. Marginal Utility is the change in total utility resulting from a one-unit change in consumption. Law of diminishing marginal utility is the notion that the more of a good that is consumed in a period of time, the smaller the increase in total utility from consuming one more unit.