An indifference curve is a graph used in economics to represent the various combinations of two goods or commodities that consumers can choose, where each point on the curve provides equal satisfaction (utility) to an individual. It is used to describe the point where individuals have no particular preference for either one good or another based on their relative quantities. The curve is typically shown as convex to the origin.

Indifference curves are used by economists to explain the tradeoffs that people consider when they encounter two goods that they wish to buy. Because people are constrained by a limited budget, they cannot purchase everything. Instead, a cost-benefit analysis must be considered. Indifference curves visually depict this tradeoff by showing which quantities of two goods provide the same utility to a consumer (i.e., where they remain indifferent) .

The slope of an indifference curve, known as the marginal rate of substitution, shows the rate at which consumers are willing to give up one good in exchange for more of the other good. For most goods, the marginal rate of substitution is not constant, so their indifference curves are curved.

In summary, an indifference curve is a tool used in economics to describe the point where individuals have no particular preference for either one good or another based on their relative quantities. It is a graphical representation of the various combinations of two goods that consumers can choose, where each point on the curve provides equal satisfaction (utility) to an individual. Indifference curves are used to explain the tradeoffs that people consider when they encounter two goods that they wish to buy, and the slope of an indifference curve shows the rate at which consumers are willing to give up one good in exchange for more of the other good.