normal, inferior, and Giffen goods

Not all goods behave the same way when your income changes. Get a raise and you might buy more steak but less instant noodles; the steak is a normal good and the noodles, oddly, an inferior good. A third, much rarer creature, the Giffen good, behaves so strangely that people buy more of it when its price rises. These three labels sort goods by how demand reacts to income and price.

A normal good is one you buy more of as your income rises, like restaurant meals, holidays, or better clothes; most goods are normal. An inferior good is one you buy less of as you grow richer, not because it is poor quality but because you can now afford a preferred alternative, like bus rides giving way to taxis, or cheap supermarket-brand food giving way to premium brands. Inferior is a statement about income response, not about being bad. The Giffen good is the exotic case: a strongly inferior staple that takes up so much of a poor household's budget that when its price rises, the household feels poorer, cannot afford the costlier alternative, and so buys even more of the cheap staple, an upward-sloping demand. Possible historical examples have been argued for staple grains, but clear real-world cases are disputed and genuinely hard to find.

These categories matter because they connect income changes to demand and warn against assuming the law of demand never bends. Income elasticity of demand makes the idea precise: positive for normal goods, negative for inferior goods. During a recession, demand for inferior goods can actually rise as households trade down, which is why economists track them as a kind of economic mood ring. The Giffen case, meanwhile, is a reminder that the usual downward-sloping demand curve is a strong tendency, not an unbreakable law.