Attribute-based access control defines a new access control paradigm whereby access rights are granted to users through the use of policies which combine attributes together. The policies can use any type of attributes (user attributes, resource attributes, etc.). Attributes can be compared to static values or to one another thus enabling relation-based access control.
One standard that implements attribute- and policy-based access control is XACML, the eXtensible Access Control Markup Language.
External Links
ATTRIBUTE BASED ACCESS CONTROL (ABAC) - OVERVIEW Unified Attribute Based Access Control Model covering DAC, MAC and RBAC