The law of demand

The law of demand expresses a relationship between the quantity
demanded and its price. It expresses an inverse relationship between
price and quantity demanded.
 
The law of demand states that the higher the price, the less the amount demanded and the lower the price, the greater the amount demanded.
 
It can be illustrated by a downward sloping demand curve. The law of demand can be explained by: Law of diminishing marginal utility; Substitution effect; and Income effect.