LDAP authentication is the process of verifying the identity of a user by validating their credentials against an LDAP server. LDAP stands for Lightweight Directory Access Protocol, which is a widely adopted protocol for accessing and managing directory information services. LDAP authentication is accomplished through a bind operation, where the client sends a bind request to the LDAP server along with the users identifier (i.e., username or email) and password. The LDAP server then verifies the provided username and password against its database. If the credentials are valid, the user is granted access to the requested resource; otherwise, access is denied.

LDAP is often used as a central hub for authentication, and it provides a standardized method for storing and retrieving data in a hierarchical directory structure. LDAP directories can store information such as users, attributes about those users, group membership privileges, and more. LDAP is widely used to build central authentication servers, which contain usernames and passwords for all the users within a network. Any-and-all applications and services can connect to the LDAP server to authenticate and authorize users. LDAP is also used by other services for authentication and/or authorization, such as in Active Directory where Kerberos is used in the authentication step, while LDAP is used in the authorization step.