Active Directory

Active Directory (AD) is a directory service

Created by Microsoft for Windows domain networks

It is included in most Windows Server operating systems

Server computers that run Active Directory are called domain controllers

An AD domain controller authenticates and authorizes all users and computers in a Windows domain type network

—Assigning and enforcing security policies for all computers and installing or updating software. For example, when a user logs into a computer that is part of a Windows domain, Active Directory checks the submitted password and determines whether the user is a system administrator or normal user.

Active Directory makes use of Lightweight Directory Access Protocol (LDAP) versions 2 and 3, Kerberos and DNS.

The Lightweight Directory Access Protocol (LDAP; pron.: /ˈɛldæp/) is an application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network.

Directory services may provide any organized set of records, often with a hierarchical structure, such as a corporate email directory. Similarly, a telephone directory is a list of subscribers with an address and a phone number.