The Authentication, Authorisation & Accountability (AAA) chapter presents the general foundations of access control and some significant instantiations that have emerged as IT kept spreading into new application areas. It will survey modes of user authentication and the way they are currently deployed, authentication protocols for the web, noting how new use cases have led to a shift from authentication to authorisation protocols, and the formalisation of authentication properties as used in today’s protocol analysis tools. On accountability, the focus is on the management and protection of audit logs. We speak with CyBOK Authentication, Authorisation & Accountability (AAA) author Dieter Gollmann for an introductory overview of the topic.