What is a role (Rolle), and what is role-based access control (RBAC)?

A role is a collection of permissions for groups of subjects tied to a particular function or task in the organisation; RBAC is access control in which a relying party authorises access to a resource on the basis of the subject's roles in an organisation.

Roles decouple permissions from individuals: you grant "accountant" the rights and assign people to the role, so joiners and leavers do not require rule changes.

Go deeper:

• Role-based access control (Wikipedia) — roles, permissions and the NIST RBAC model levels.
• NIST RBAC project — the standard's home at NIST: model levels, FAQ and case studies.