Absolutism is a system of government in which the ruler has absolute power. This means that the ruler is not subject to any checks or balances, and his or her power is not limited by law or custom. Absolutism reached its peak in Europe during the 17th and 18th centuries, but it began to decline in the late 18th century, as Enlightenment ideas about individual rights and the rule of law gained popularity. Today, there are no pure absolutist states left in the world, but there are still some countries where the ruler has a great deal of power.