LDAP (Lightweight Directory Access Protocol) is an application protocol that is widely used in computer technics. By means of the LDAP server it is possible to run user administration from one central system. Only one single password is necessary. The web client serves as a data transmission device between the central system and the individual database. Hence, LDAP allows you to administrate your users centrally.
Background information: LDAP allows the query and modification of information of a directory service by means of the TCP/IP network. One important characteristic is its hierarchical setup, which for example MySQL does not use (MySQL possesses an ordinary, tabular structure). The data structure of an LDAP directory is like a hierarchical tree with roots, branches/twigs and leaves. The root (root, suffix) is the topmost data object, below it one finds the higher structures. If you allocate to a user two groups of different hierarchical status (see 10.2.2.1), then the hierarchical status of the user corresponds to the hierarchical status of the one of the two groups which is hierarchically highest.