Giffen commodities are those commodities

Giffen commodities are those commodities for which demand increases as price increases. This is contrary to the law of demand which states that as the price of a good increases, the quantity demanded decreases. Giffen goods are usually inferior goods that are consumed out of necessity and have no close substitutes. As the price of the Giffen good increases, consumers have less income to spend on other goods, so they end up buying more of the Giffen good despite the higher price. This is because the income effect of the higher price outweighs the substitution effect.