Lightweight Directory Access Protocol, LDAP, is a protocol to access directory services, where you can save the hierarchical structure of your company, your users and your access roles.
Since LDAP is used to allow access control to many applications, this service is used as a single sign on solution, allowing user to authenticate in many applications using a single login name and password.
Links:
- OpenLDAP: open source software that implements an LDAP-accessible directory service
- PHPLdapAdmin: LDAP administration web interface