A guard is either a person or an organisation. It may be a person who looks after the safety of people or property, and/or make sure prisoners do not escape. It may also be a part of the military. It can also be an object, a fireguard for example.
Examples:
They may also be elite military forces which guards a head of state:
Because the head of state often wishes to be protected by the best soldiers available, their numbers and organisation may be expanded to carry out additional tasks:
Some times the term has been used for the complete military organisation of a state, because it guards the state from its enemies:
It can also be a term used in sports such as Brazilian Jiu Jitsu, Judo or Submission Wrestling
A guard is also a railway employee who (normally) travels in the last vehicle of a train and is responsible for the safety of the train itself.
See also: