What is the definition of a "normal good"?

A "normal good" is one that follows the conventional pattern of demand change in response to income changes. As income level goes up for a person or community, the level of demand for a normal good increases as well. At lower income levels, quantity demanded is also lower.

Higher-priced vehicles are an example of a normal good. When people in a community have a relatively high level of income, they have greater ability to purchase luxury vehicles. In contrast, a population with a lower average income level wouldn't allow for significant demand of such vehicles. Services such as bus or subway transportation are also normal goods.