Domain Is It
There are also many types of subdomains.
Domain is it. A domain has a domain controller that governs all basic domain functions and manages network security. A domain is a network of computers and devices that are controlled by one set authority and that have specific guidelines. Domain names are used in various networking contexts and for application specific naming and addressing purposes.
A domain name is an identification string that defines a realm of administrative autonomy authority or control within the internet. 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.