What is organizational unit in active directory?

Domain: A security boundary for the network On a local area network (LAN), a domain is a subnetwork made up of a group of clients and servers under the control of one central security database. Within a domain, users authenticate once to a centralized server known as a domain controller, rather than repeatedly authenticating to individual servers and services. Individual servers and services accept the user based on the approval of the domain controller. Organisational Unit: A part of Active Directory used to Organise and Manage the objects of AD An organizational unit (OU) is a subdivision within an Active Directory into which you can place users, groups, computers, and other organizational units. You can create organizational units to mirror your organization's functional or business structure. Each domain can implement its own organizational unit hierarchy. If your organization contains several domains, you can create organizational unit structures in each domain that are independent of the structures in the other domains. The term "organizational unit" is often called as "OU" in casual conversation. "Container" is also often applied in its place, even in Microsoft's own documentation. All terms are considered correct and interchangeable.