Directories become the points of reference for applications and user services.
They help find a printer in a field office, locate a user and direct an e-mail, or verify that a user has access rights to a particular file. Directories are becoming increasingly important as business networks expand to include connections with business partners and customers. Managing a single directory for multiple functions greatly reduces cost and complexity. And Microsoft has a good chance of seeing third-party applications integrate with Active Directory. Microsoft created the Active Directory Service Interface to rally third-party application support.