Active Directory

Active Directory (AD) is a directory service for use in a Windows Server environment. It is a distributed, hierarchical database structure that shares infrastructure information for locating, securing, managing, and organizing computer and network resources including files, users, groups, peripherals and network devices.

Active Directory is Microsoft’s own directory service for use in Windows domain networks. It provides authentication and authorization functions, as well as providing a framework for other such services. The directory itself is an LDAP database that contains networked objects. Active Directory uses the Windows Server operating system.

When people talk about Active Directory, they typically mean Active Directory Domain Services, which provides full-scale, integrated authentication and authorization services.

Before Windows 2000, Microsoft’s authentication and authorization model required breaking down a network into domains, and then linking those domains with a complicated, and sometimes, unpredictable system of one- and two-way trusts. Active Directory was introduced in Windows 2000 as a way to provide directory services to larger more complex environments.