AD LDS (Active Directory Lightweight Directory Service)

AD LDS is capable of running as a service on computers running Microsoft Windows Server 2003. AD LDS shares its code base with Active Directory and provides the same functionality as Active Directory, including an identical API, but does not require the creation of domains or domain controllers.

Like Active Directory, AD LDS provides a Data Store, which is a hierarchical data store for storage of directory data, a Directory Service with an LDAP Directory Service Interface. Unlike Active Directory, however, multiple AD LDS instances can be run on the same server, with each instance having its own applications making use of the specific AD LDS directory service instance.