Active Directory (AD) is a directory service that Microsoft developed for Windows domain networks. It is included in most Windows Server operating systems as a set of processes and services. Initially, Active Directory was only in charge of centralized domain management. Starting with Windows Server 2008, however, Active Directory became an umbrella title for a broad range of directory-based identity-related services. Active Directory Domain Services (AD DS) is the cornerstone of every Windows domain network. It stores information about members of the domain, including devices and users, verifies their credentials and defines their access rights. The server (or the cluster of servers) running this service is called a domain controller. A domain controller is contacted when a user logs into a device, accesses another device across the network, or runs a line-of-business Metro-style app side loaded into a device.