Normal Goods:Normal goods are consumer goods for which demand increases as a consumer's income increases. These are goods that people tend to consume more of as they become wealthier.
Superior Goods: Superior goods are a type of normal good for which the demand increases more than proportionally as a consumer's income increases. These are goods that people strongly prefer to consume more of as they become wealthier.
Income Elasticity of Demand:Income elasticity of demand measures the responsiveness of demand for a good to a change in a consumer's income. Inferior goods have a negative income elasticity of demand.