Your highness define
Your Highness is a form of address used for certain royal persons. Your Majesty is a different style associated with a reigning sovereign in many monarchies. The correct title depends on the particular royal house, person, and occasion.
Meaning and context
Do not assume that every prince, princess, or monarch uses exactly the same form. Official protocols distinguish styles, titles, and ranks. A familiar expression from a film is not reliable guidance for a formal invitation or official correspondence.

Examples and usage
In a fictional dialogue, Your Highness may address a prince. In a real letter, first check the person’s official style and the institution’s instructions. A person’s title in third-person reference can differ from the direct form used when addressing them.
What to check
The phrase can also be used jokingly or sarcastically outside a royal setting. That informal use does not confer a title and may sound insulting. For an actual protocol question, follow the relevant royal household’s current guidance rather than generalizing across countries.
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