An indifference curve represents a graph showing different combinations of two goods that provide the same level of utility or satisfaction to a consumer. Each point on the curve indicates a combination where the consumer feels indifferent between the two goods, meaning they have no preference for one combination over another. The concept connects to budget constraints, which illustrate how consumers maximize their satisfaction given their income limits, and also ties into income and substitution effects that show how changes in prices or income levels shift consumer choices along these curves.