Authority refers to power exercised by a person in virtue of his/her position or jurisdiction or a right to command. Authority also refers to one who is claimed in support of opinions. Authority can be used in three senses. It can be used to mean:
1. a principal’s operative act.
2. a physical document executed by the principal, or
3. the legal right or permission to act on behalf of another.
There are different types of authority and the meaning of each vary accordingly.