Substitute Goods: Substitute goods are products that can be used in place of each other. For example, if the price of coffee increases, some consumers may switch to tea as a substitute.
Complementary Goods: Complementary goods are products that are typically consumed together. An example would be peanut butter and jelly - an increase in demand for one often leads to an increase in demand for the other.
Elasticity of Demand: Elasticity of demand measures how responsive the quantity demanded is to changes in price. If consumer tastes change drastically for a product, it can affect its elasticity of demand.