Lightweight Directory Access Protocol (LDAP) is a client/server protocol used to access and manage directory information. It reads and edits directories over Internet Protocol (IP) networks and runs directly over Transmission Control Protocol (TCP)/IP using simple string formats for data transfer. It was originally developed as a front end to X.500 Directory Access Protocol.
Lightweight Directory Access Protocol is also known as RFC1777 - Lightweight Directory Access Protocol (LDAP).
Source: https://www.techopedia.com/definition/2439/lightweight-directory-access-protocol-ldap