Complementary goods are commodities that depend on each other such that in increase in the price of one good causes a decrease in the demand for the related good. For example, an increase in the price of [[french toast ]] could cause a decrease in the demand for [[maple syrup]], because those two goods are often consumed together. An increase in the price of [[salad dressing ]] could cause a decrease in demand for [[salad]].
Complementary goods are the opposite of [[substitute goods]].