Indifference curves are a graphical representation of a consumer's preferences for different combinations of two goods. They show all the combinations of two goods that provide the same level of satisfaction or utility to the consumer. The slope of the indifference curve represents the rate at which the consumer is willing to trade one good for another. The higher the slope, the more willing the consumer is to give up one good to obtain more of the other. Indifference curves are used to analyze consumer behavior and to derive demand curves for goods.