Resources > Domain Names

This gives information about domain names:

• About Domain Names
• Domain Name Availability
• Where to Find Registrars

About Domain Names 

A domain name is an address on the Internet. For example:

www.upsdell.com
www.upsdell.ca

The prefix ‘www.’ is traditional, but isn’t always present: depending on how the server is set up, the 'www.' may be required, optional, forbidden, or replaced by something else. For my upsdell.com domain the 'www.' is optional.

The main part of the name (‘upsdell’ in the above example) may have only the letters a-z, the digits 0-9, and a dash, with no dash at the beginning or end, and may not exceed 63 characters. Exception: in June 2003 an Internationalized Domain Names (IDN) standard was issued to allow international characters from 350+ languages in domain names.

In some cases the domain name has subdomains. E.g. BrowserNews might be a subdomain of the upsdell.com domain: hence the address BrowserNews.upsdell.com.

The suffix (e.g. ‘.com’) is called the TLD (Top Level Domain). There are conventions about TLDs:

• .aero is for the air-transport industry.
• .arpa is for Internet infrastructure purposes.
• .asia is for Asian sites.
• .biz is for businesses.
• .cat is for the Catalan language community.
• .com is for businesses.
• .coop is for coöperatives.
• .edu is for US institutes of higher education; earlier .edu was also for non-US institutes.
• .eu is for those in the EU.
• .gov is for US government sites.
• .info is for information suppliers.
• .int is for international treaty organizations.
• .jobs is for the international human resource management community.
• .mil is for US military sites.
• .mobi is for mobile devices.
• .museum is for museums.
• .name is for personal sites.
• .net is for network-related organizations.
• .org is primarily for charities and non-commercial or non-profit organizations.
• .post is for the Universal Postal Union.
• .pro is for accredited professionals, with sub-domains .cpa.pro for accountants, .eng.pro for engineers, .med.pro for doctors, .law.pro for lawyers, etc.
• .tel is for accessing communications devices (not yet available).
• .travel is for the travel industry.
• .xxx is for adult content, e.g. porn.
• a 2-letter country code — e.g. .ca for Canada — is for a designated country. Some nations precede this with a sub-domain name identifying a region or a type of site: e.g., in Canada addresses of government sites for the province of Ontario end in .on.ca; in the UK addresses of commercial sites end in .co.uk.
• IDNs, International Domain Names using non-Latin characters are appearing for some countries.

More TLDs will likely be approved in the future.

More TLDs, sponsored by any entity with enough money to pass an approval process, will appear in the future, potentially allowing the appearance of a very large number of new TLDs. For example: .canon.

ICANN provides a resource regarding TLDs in a document titled Universal Acceptance of all Top-Level Domains. It also offers a resource about the introduction of new TLDs at a page titled New gTLD Program.