The Howdy Glossary

XACML (eXtensible Access Control Markup Language) is an XML-based standard for access control policies and their management. It enables fine-grained access control over resources by using a set of rules that can be evaluated automatically. XACML describes how to encode authorization logic in freeform policies, allowing them to work across various application domains without the need for custom programming. The language consists of a policy language for expressing access control requirements and a request/response language for communicating these requirements between components involved in enforcing access controls.

The syntax of XACML uses XML elements to represent users, resources, actions, conditions, obligations, and advice. This declarative approach makes it possible to create complex authorization scenarios by combining simple rules into more sophisticated outcomes. Implementers use the standard’s reference architecture as a guide when designing systems that incorporate XACML into their security models.

Although not as widely used as some other methods of controlling access such as role-based or attribute-based access control (ABAC), XACML provides an advanced means of ensuring only authorized entities are granted permission to perform specific operations within an information system or application platform.