From Wikipedia, the free encyclopedia
This article is about domain names in the Internet. For other uses, see
Domain.
The hierarchy of labels in a fully qualified domain name.
A
domain name is an identification
string that defines a realm of administrative autonomy, authority or control within the
Internet. Domain names are formed by the rules and procedures of the
Domain Name System (DNS). Any name registered in the DNS is a domain name. Domain names are used in various networking contexts and application-specific naming and addressing purposes. In general, a domain name represents an
Internet Protocol (IP) resource, such as a personal computer used to access the Internet, a server computer hosting a
web site, or the web site itself or any other service communicated via the Internet. In 2017, 330.6 million domain names had been registered.
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Domain names 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 the prominent domains
com,
info,
net,
edu, and
org, and the
country code top-level domains (ccTLDs). Below these top-level domains in the DNS hierarchy are the second-level and third-level domain names that are typically open for reservation by end-users who wish to connect local area networks to the Internet, create other publicly accessible Internet resources or run web sites.
The registration of these domain names is usually administered by
domain name registrars who sell their services to the public.
A
fully qualified domain name (FQDN) is a domain name that is completely specified with all labels in the hierarchy of the DNS, having no parts omitted. Labels in the Domain Name System are
case-insensitive, and may therefore be written in any desired capitalization method, but most commonly domain names are written in lowercase in technical contexts.
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![[icon]](https://en.wikipedia.org/wiki/File:Wiki_letter_w_cropped.svg){kind=small}
