What is the relationship between complementary goods?

Complementary goods are products that are used together, meaning that the consumption of one good enhances the consumption of the other. This relationship is characterized by joint demand; when the price of one good rises, the demand for its complement typically decreases because the overall cost of using both goods together has increased. For example, if the price of printers increases, the demand for ink cartridges may fall, as people are less likely to purchase a printer if its associated costs are high.

This interconnectedness highlights that the use of one good is dependent on the other, where an increase in demand for one generally leads to an increase in demand for the other, as they fulfill complementary roles in consumption. Therefore, the statement that they are in joint demand, with the use of one necessitating the other, accurately captures the essence of the relationship between complementary goods.