Bread and butter, car and petrol are examples of goods which have

Bread and butter, car and petrol are examples of goods having joint demand. Joint demand occurs when two goods are consumed together - one is useless without the other. Bread requires butter to be eaten as intended, and cars require petrol to function. These are complementary goods where the demand for one creates demand for the other. This differs from composite demand (multiple uses of same good), derived demand (demand dependent on another product), or autonomous demand (independent demand).