Specific to the internet, the term domain can refer to how the internet is structured, and domain also refers to how an organization's network resources are organized. In general, a domain is an area of control or a sphere of knowledge.
What is an internet domain?
An internet domain is an administrative structure for organizing, delivering and accessing services on the internet. The terms "domain" and "domain name" are often used interchangeably (in context of the internet) because the domain structure is associated with how domains are named.
Internet domains are set up in accordance with the Domain Name Service (DNS), an application layer protocol and service used on networks to translate host names to their associated IP addresses. DNS is an essential component of the internet. It is implemented as a decentralized, hierarchical system that's distributed globally across a conglomeration of DNS servers. The service acts as a giant directory for resolving domain names to IP addresses and IP addresses to domain names, irrespective of where the domains are located.
The DNS system allows internet users to access content by remembering a name rather than an IP address. For example, DNS makes it possible for users to type techtarget.com in a browser to connect to the TechTarget website, without knowing the associated IP address.
Internet domains are identified by unique IP addresses. These addresses make it possible for a device connected to the internet to communicate directly with a specific domain. DNS simplifies communications using a hierarchical naming structure.
At the top of this hierarchy is the Root domain, which serves as the parent node for all internet domains. The root domain contains multiple top-level domains (TLDs) that sit directly beneath it in the DNS hierarchy. TLDs identify geographic or purpose commonality, such as a nation or commercial enterprise. For example, TLDs include .com, .net, .org, .gov and several other domains, including country codes.
Individual domains -- such as techtarget.com, usda.gov or redcross.org -- sit directly beneath the TLDs. Each second-level domain is associated with a specific TLD, as indicated by the final component of the domain name. For example, techtarget.com is located within the .com TLD, usda.gov is part of the .gov TLD, and redcross.org is within the .org TLD. A second-tier domain can also include subdomains, as in searchstorage.techtarget.com or searchdatabackup.techtarget.com, which are part of the second level techtarget.com domain.
