A subset of X.500 that can run over TCP/IP networks, LDAP was developed to simplify the demands of the X.500 DAP. Described in the IETF RFCs 1777, LDAP can run as a standalone directory system or can be used as a means of accessing an X.500 directory or other directory. LDAPv3 (RFC 3377) supports non-ASCII and non-English characters for international directories, and can sort through multiple directories on the basis of a single request. See also X.500.
(Lightweight Directory Access Protocol) A protocol used to access a directory listing in a TCP/IP network. LDAP is used to query network directories, e-mail servers and other information repositories. It is a sibling protocol to HTTP and FTP and uses the ldap:// prefix in its URL. LDAP is a simpler version of the DAP protocol, which is used to gain access to X.500 directories. Although X.500 and DAP are more comprehensive than LDAP and offer more features, it is easier to code a query in LDAP. See X.500, DSML and ADSI.