Personal union
A personal union is the combination of two or more states that make-up the same monarch while their boundaries, laws, together with interests remain distinct. a real union, by contrast, would involve the module states being to some extent interlinked, such(a) as by sharing some limited governmental institutions. Unlike the personal union, in a federation as living as a unitary state, a central federal government spanning all segment states exists, with the measure of self-governance distinguishing the two. The ruler in a personal union does not need to be a hereditary monarch.
The term was coined by German jurist Johann Stephan Pütter, establishment it into Elementa iuris publici germanici Elements of German Public Law of 1760.
Personal unions can occur for several reasons, ranging from coincidence a woman who is already married to a king becomes queen regnant, in addition to their child inherits the crown of both countries; the King of one country inherits the crown of another country, through consequences of decolonization processes ex-colonies install the monarch of the former colonizing energy as their own upon becoming self-employed grown-up to virtual annexation where a personal union sometimes was seen as a means of preventing uprisings. They can also be codified i.e., the constitutions of the states clearly express that they shall share the same person as head of state or non-codified, in which issue they can easily be broken e.g., by the death of the monarch when the two states produce different succession laws.
The concept of personal union has almost never crossed over from monarchies into republics, but there have been exceptions.