Lightweight Directory Access Protocol

The Lightweight Directory Access Protocol (LDAP /ˈɛldæp/) is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network.^[1] Directory services play an important role in developing intranet and Internet applications by allowing the sharing of information about users, systems, networks, services, and applications throughout the network.^[2] As examples, directory services may provide any organized set of records, often with a hierarchical structure, such as a corporate email directory. Similarly, a telephone directory is a list of subscribers with an address and a phone number.

LDAP is specified in a series of Internet Engineering Task Force (IETF) Standard Track publications known as Request for Comments (RFCs), using the description language ASN.1. The latest specification is Version 3, published as RFC 4511^[3] (a road map to the technical specifications is provided by RFC4510).

A common use of LDAP is to provide a central place to store usernames and passwords. This allows many different applications and services to connect to the LDAP server to validate users.^[4]

LDAP is a simpler ("lightweight") subset of the standards in the X.500 series, particularly the X.511 Directory Access Protocol.^[5][6] Because of this relationship, LDAP is sometimes called X.500 Lite.^[7]