active directory is centrifical database.Its provide to central authentication and autherization services for n/w computers.it is also provide apply security policies
Active Directory is a directory service used to store information about the network resources across a domain.An 'Active Directory' (AD) structure is a hierarchical framework of objects. The objects fall into three broad categories: resources (e.g., printers), services (e.g., email), and users (user accounts and groups). The AD provides information on the objects, organizes the objects, controls access and sets security.
