An interregnum is a period between monarchs, between popes of the Roman Catholic Church, emperors of Holy Roman Empire, Polish kings (elective monarchy) or between consuls of the Roman Republic. It can also refer any gap in the continuity of a government, organization, or social order.
In some monarchies, such as the United Kingdom, an interregnum is usually avoided due to a rule described as "the king is dead, long live the King", i.e. the heir to the throne becomes a new monarch immediately on his predecessor's death or abdication. This famous phrase signifies the continuity of sovereignty. This is not so in other monarchies where the new monarch's reign begins only with coronation or some other formal or traditional event.
Pope's interregnum (or sede vacante) [change]
An interregnum occurs also upon the death of the Roman Catholic Pope, though this is generally known as a sede vacante (vacant seat). The interregnum ends immediately upon election of the new Pope by the College of Cardinals.