Reign

A reign is the period of time that a monarch (a king, queen, emperor, etc.) rules over a country. It can also be the period of time that a spiritual leader rules in a particular office. For example, the reign of a pope, dalai lama, patriarch etc. A reign can also be used for an office or championship. In many cases a reign lasts until the monarch (or leader) resigns, dies, or is removed. A monarch's reign was sometimes used to mark time officially. In Anglo-Saxon England for example, many royal documents were dated by the regnal year of the king.Michael Jones, A Handbook of Dates: For Students of British History (Cambridge: Cambridge University Press, 2004), p. 21 This lasted until about the 10th century.

 Current Longest Reigning Monarchs  
Some of the longest reigning current monarchs are:

Elizabeth II, United Kingdom, 62+ years .
Sikiru Kayode Adetona, Nigeria, 55+ years. 
Hassanal Bolkiah, Brunei, 47+ years.
Margrethe II of Denmark, 42+ years.
Sultan bin Muhammad Al-Qasimi, United Arab Emirates, 42+ years.
Carl XVI Gustaf of Sweden 41+ years.

Some of the longest reigning monarchs of all time are:
Sobhuza II, Swaziland, reigned for 82 years, 253 days.
Bernard VII, Lord of Lippe, reigned for 81 years, 234 days.
Bhagvat Singh, ruler of Gondal, India, reigned for 74 years, 87 days.
Louis XIV of France reigned for 72 years, 110 days.

 Shortest Reigning Monarchs in History 
Some of the shortest reigns in history are:
Louis Antoine, Duke of Angoulême as "Louis XIX of France", reigned for 20 minutes.
Dipendra of Nepal, reigned for 56 hours (in a coma).
Dục Đức reigned as Emperor of Vietnam for 3 days.
Lady Jane Grey reigned as Queen of England for 9 days.
Edward V of England was King of England for 2 months, 16 days.
Dafydd ap Gruffydd was the Prince of Wales (last independent ruler) for 6 months, 11 days.

 References 

Category:Monarchy