Since every (X , Y) combination will have an indifference curve passing through it, we can add a third axis stretching upward from the bottom left corner of the figure measuring the degree to which the individual's preferences are satisfied, and visualize the infinitely many indifference curves as representing a smooth surface that rises as the consumption of commodities X and Y increase.
In microeconomic theory, a graph showing different bundles of goods between which a consumer is indifferent.