top-level domain

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top-level domain

(networking)
The last and most significant component of an Internet fully qualified domain name, the part after the last ".". For example, host wombat.doc.ic.ac.uk is in top-level domain "uk" (for United Kingdom).

Every other country has its own top-level domain, including ".us" for the U.S.A. Within the .us domain, there are subdomains for the fifty states, each generally with a name identical to the state's postal abbreviation. These are rarely used however. Within the .uk domain, there is a .ac.uk subdomain for academic sites and a .co.uk domain for commercial ones. Other top-level domains may be divided up in similar ways.

In the US and some other countries, the following top-level domains are used much more widely than the country code:

.com - commercial bodies .edu - educational institutions .gov - U. S. government .mil - U. S. armed services .net - network operators .org - other organisations

Since the rapid commercialisation of the Internet in the 1990s the ".com" domain has become particularly heavily populated with every company trying to register its company name as a subdomain of .com, e.g. "netscape.com" so as to make it easy for customers to guess or remember the URL of the comany's home page.

United Nations entities use the domain names of the countries where they are located. The UN headquarters facility in New York City, for example, is un.org.

Several new top-level domains are about to be added (Oct 1997): .nom - individual people .rec - recreational organisations .firm - businesses such as law, accounting, engineering .store - commercial retail companies .ent - entertainment facilities and organisations

Internet domain name

An Internet domain name is a unique name of an organization or person on the Internet. The name is combined with a generic top-level domain (gTLD), such as .com or .org. For example, computerlanguage.com is the domain name for the publisher of this encyclopedia. By 2019, there were more than 300 million registered domain names.

Under ICANN's "New gTLD" program, communities, industries and organizations can create their own top-level domain names (see New gTLD).

Registration Is Required
In order for a domain name to be visible on the Internet, it must first be registered with any one of hundreds of registrars, which will verify that the name is absolutely unique. See registrar.

Dub-Dub-Dub or Whatever
In order to access The Computer Language Company website, www.computerlanguage.com is typed into the browser's address bar (see URL). The WWW, often verbalized as "dub-dub-dub," is a mnemonic commonly used for the hostname of a company's Web server. However, WWW is only a recommendation, and Web servers can be assigned any hostname. In addition, most companies configure their Web servers to not require a hostname. For example, computerlanguage.com without the WWW is sufficient. See hostname and DNS.

Different mnemonics are also widely used to identify sections of a site; for example, support.computerlanguage.com could be a valid address, in which case the word SUPPORT could not be omitted when typing the name.

Generic Top-Level Domains


In 1985, the following generic top-level domains (gTLDs) were created.
Unrestricted gTLDs.com   commercial
 .net   network oriented
 .org   non-profit organization

  Restricted gTLDs.edu   accredited U.S. educational
 .gov   U.S. government agencies
 .mil   U.S. military
 .int   international treaties (1988)


More Domain Names
Starting in 2000, ICANN added more domains. Sponsored domains means that their use is reserved for a particular community, or registration is restricted to a certain type of applicant (see sTLD).

Sponsored Top-Level DomainssTLD    Purpose.aero    global aviation community
 .asia    Pan-Asia/Asia Pacific region
 .cat     Catalan community
 .coop    cooperatives
 .jobs    human resources/employment
 .mobi    mobile products/services
 .museum  museums
 .post    postal sector
 .pro     licensed professionals
 .tel     contacts (see  .tel)
 .travel  travel industry
 .xxx     X-rated


  Unsponsored Top-Level Domains.biz     businesses
 .info    information service
 .name    individuals


Countries Also Have Domain Names
Every country has a top-level domain; for example, .ca for Canada and .fr for France. The U.S. country code is .us, but it is not widely used. See country code, New gTLD, ICANN, IP address and FQDN.

TLD

(Top-Level Domain) The highest-level in the Internet domain naming system. Officially called a "generic top-level domain" (gTLD), it is also known as a "domain suffix" or "domain extension," because the designation is added to the end of the domain name. For example, .com is the gTLD in www.lenovo.com. For details, see Internet domain name.
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