A principal in computer security is an entity that can be authenticated by a computer system or network. It is referred to as a security principal in Java and Microsoft literature.^[1]

Principals can be individual people, computers, services, computational entities such as processes and threads, or any group of such things.^[1] They need to be identified and authenticated before they can be assigned rights and privileges over resources in the network. A principal typically has an associated identifier (such as a security identifier) that allows it to be referenced for identification or assignment of properties and permissions.