Household Division is a term used principally in the Commonwealth of Nations

Commonwealth of Nations

The Commonwealth of Nations, normally referred to as the Commonwealth and formerly known as the British Commonwealth, is an intergovernmental organisation of fifty-four independent member states...

 to describe a country’s most elite or historically senior military units, or those military units that provide ceremonial or protective functions associated directly with the head of state

Head of State

A head of state is the individual that serves as the chief public representative of a monarchy, republic, federation, commonwealth or other kind of state. His or her role generally includes legitimizing the state and exercising the political powers, functions, and duties granted to the head of...

.
In medieval Western Europe

Western Europe

Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...

, the most able warriors were pressed into service as the personal bodyguard

Bodyguard

A bodyguard is a type of security operative or government agent who protects a person—usually a famous, wealthy, or politically important figure—from assault, kidnapping, assassination, stalking, loss of confidential information, terrorist attack or other threats.Most important public figures such...

s to the monarch and other members of the royal or imperial household; as a result, Household troops are commonly referred to as Guards.