LDAP is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network. The latest specification can be found at the ietf
OpenLDAP is an open source implementation of the Lightweight Directory Access Protocol.
An OpenLDAP Infrastructure is maintained by the ITS Linux System Administration and is used to provide the Directory generated by idm.bfh.ch published also in Active Directory.