LDAP (Lightweight Directory Access Protocol) is a protocol used by Active Directory and other directory services for managing network resources like users, computers, and printers. It provides a standardized way to access and modify data stored in a hierarchical directory structure, such as Active Directory. LDAP is used for querying and updating information in the directory, and it provides authentication services for users connecting to the network. Active Directory can be fully managed through LDAP by administrators, system management tools, and applications for easier overall management.