LDAP (Lightweight Directory Access Protocol) is a software protocol for enabling anyone to locate organizations, individuals, and other resources such as files and devices in a network, whether on the public Internet or on a corporate intranet. LDAP is a "lightweight" (smaller amount of code) version of Directory Access Protocol (DAP), which is part of X.500, a standard for directory services in a network. LDAP is lighter because in its initial version it did not include security features.
The current version of the LDAP is version 3(v3) published as RFC 4510.
LDAP was originally created by Tim Howes of the University of Michigan, Steve Kille of Isode Limited, and Wengyik Yeong of Performance Systems International in 1993. The protocol was originally intended to be a lightweight alternative protocol for accessing X.500 directory services through the simpler TCP/IP protocol stack.
The X.500 directory services were accessed via the X.500 Directory Access Protocol (DAP), which required the Open Systems Interconnection (OSI) protocol stack. The advent of LDAP removed the necessity of the OSI protocol.
The version 3 of the LDAP was developed by Tim Howes and Steve Kille in 1997.