Editing Domain name (section)

{{Short description|Identification string in the Internet}}
{{About|domain names in the Internet||Domain (disambiguation)}}
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[[File:An annotated example of a domain name.png|thumb|An annotated example of a domain name]]

In the [[Internet]], a '''domain name''' is a [[String (computer science)|string]] that identifies a realm of administrative autonomy, authority or control. Domain names are often used to identify services provided through the Internet, such as [[website]]s, [[email]] services and more. Domain names are used in various networking contexts and for application-specific naming and addressing purposes. In general, a domain name identifies a [[network domain]] or an [[Internet Protocol]] (IP) resource, such as a personal computer used to access the Internet, or a server computer.

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 organized in subordinate levels (''[[subdomain]]s'') of the [[DNS root]] domain, which is nameless. The first-level set of domain names are the ''[[top-level domain]]s'' (TLDs), including the ''[[generic top-level domain]]s'' (gTLDs), such as the prominent domains [[.com|com]], [[.info|info]], [[.net|net]], [[.edu|edu]], and [[.org|org]], and the ''[[country code top-level domain]]s'' (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 websites, such as "wikipedia.org". 
The registration of a second- or third-level domain name is usually administered by a [[domain name registrar]] who sell its 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. Traditionally a FQDN ends in a dot ('''.''') to denote the top of the DNS tree.<ref>{{cite book |title=TCP/IP Illustrated, Volume 1: The Protocols |publisher=[[Addison-Wesley]] |author-link=W. Richard Stevens |first=W. Richard |last=Stevens |volume=1 |edition=1 |isbn=9780201633467 |date=1994 }}</ref> 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.<ref>{{cite tech report |url=https://tools.ietf.org/html/rfc4034#section-6 |title=RFC 4034 – Resource Records for the DNS Security Extensions |year=2005 |publisher=IEFT |doi=10.17487/RFC4034 |last1=Arends |first1=R. |last2=Austein |first2=R. |last3=Larson |first3=M. |last4=Massey |first4=D. |last5=Rose |first5=S. |access-date=2015-07-05 |archive-date=2018-09-20 |archive-url=https://web.archive.org/web/20180920003106/https://tools.ietf.org/html/rfc4034#section-6 |url-status=live }}</ref>
A ''[[hostname]]'' is a domain name that has at least one associated [[IP address]].