Domain Names are web addresses, identification labels which defines an administrative autonomy, authority, or control in the Internet.
A Domain name is also hostname which identifies Internet Protocol (IP) resources such as web sites. Domain names are formed by the rules and procedures of the Domain Name System (DNS). They are used in various networking contexts and application-specific naming and addressing purposes. Domains are organized in subordinate levels (subdomains) of the DNS root domain, which is nameless.
The first-level set of domain names are the Top-level domains (TLDs), including the generic top-level domains (gTLDs), such as .COM, .NET and .ORG, and the country code Top-level domains (ccTLDs).
There are second-level and third-level domain names in the DNS hierarchy which are open for reservation by end-users as well.