This article deals with Majesty as it relates to NationStates. For more general information, see the Wikipedia article on this subject.
Variations, such as "Nordic Majesty" (Nordrige) or "Catholic Majesty" (pre-republic Boireann) are often used in diplomatic settings where there otherwise may be ambiguity.
Imperial heads such as Emperors or Empresses may use "Imperial Majesty".
A common misnomer throughout NationStates is to refer to a King or Queen as "His/Her Highness", which in RL is actually the style for either ruling or dynastic Princes and Princesses and ruling Grand Dukes and Grand Duchesses.