Constitutional monarchy is a form of government in which a monarch acts as head of state within the guidelines of a constitution, whether it be a written, uncodified, or blended constitution. This form of government differs from absolute monarchy in which an absolute monarch serves as the source of power in the state and is not legally bound by any constitution and has the powers to regulate his or her respective government.
Constitutional monarchies are sometimes referred to as limited monarchies, crowned republics or parliamentary monarchies.
Most constitutional monarchies employ a parliamentary system in which the monarch may have strictly ceremonial duties or may have reserve powers, depending on the constitution. Under most modern constitutional monarchies there is also a prime minister who is the head of government and exercises effective political power.