Under the Belgian Constitution, the Belgian monarch is styled "King of the Belgians" (French: Roi des Belges, Dutch: Koning der Belgen, German: König der Belgier) rather than "King of Belgium" in order to reflect the monarchy's constitutional and popular function.
Since 1831, there have been seven Kings of the Belgians and two regents.
Under Article 90 of the Belgian Constitution, from the death of a monarch until the swearing in of their successor or a regent, the monarch's constitutional powers are in the hands of the Council of Ministers (interregnum); this accounts for the difference of dates between the end of one reign and the beginning of the following one.