The demand for a good or service can be greatly affected by the changes in a consumer's income. We say that a good is normal if a consumer's income increases and the consumption or demand for that good also increases. Almost all goods are normal but the most notable examples would be branded and high-end goods, because people tend to buy more of them if their income increases.

On the other hand, if a customer's income increases but the demand for the good decreases, then it is said to be an inferior one. The most common examples of these goods are canned goods, thrift-bought items, and imitation products. People buy less of them when they're already making more money.