Definition - What does Domain mean?
A domain, in the context of networking, refers to any group of users, workstations, devices, printers, computers and database servers that share different types of data via network resources. There are also many types of subdomains.
A domain has a domain controller that governs all basic domain functions and manages network security. Thus, a domain is used to manage all user functions, including username/password and shared system resource authentication and access. A domain is also used to assign specific resource privileges, such as user accounts.
Techopedia explains Domain
In a simple network domain, many computers and/or workgroups are directly connected. A domain is comprised of combined systems, servers and workgroups. Multiple server types may exist in one domain - such as Web, database and print - and depend on network requirements.