Computers on the Internet, called “host computers,” are identified by both numbers and names. The number consists of four parts separated by periods, for example “188.8.131.52.” This number is commonly referred to as the “IP Address” of the computer, pinpointing the location of that computer on the Internet, so that it may be reached by other computers.
As a string of numbers is very difficult to remember, each number has a name associated with it. This is the “domain name.” Domain names have multiple levels, as shown in the corresponding diagram. All domain names contain a “top level domain,” (commonly referred to as a “TLD”). The current universally recognized top level domains are listed below. These top level domains are all approved by the Internet Corporation for Assigned Names and Numbers (“ICANN”), the administrative body governing the Internet.
- “us” – reserved for U.S. citizens, residents, businesses, or organizations and federal, state, and local governments and other country codes
- “com” – typically designating a commercial company
- “net” – typically designating a networking organization
- “org” – typically designating a non-profit organization
- “edu” – designating an educational institution
- “mil” – reserved exclusively for the United States government
- “int” – used only for registering organizations established by international treaties between governments
- “biz” – reserved for businesses
- “info” – an unrestricted top level domain for information
- “aero” – pertaining to the air transport industry
- “coop” – designating cooperatives
- “museum” – designating museums
- “name” – designating individuals
- “pro” – designating lawyers, accountants, and physicians
In addition, other top level domain registrations are available through companies like New.net, which operate outside of the regulatory scope of ICANN. These include “kids,” “law,” and “inc.” Domain name registrations with these top level domains are available for purchase by the general public, but unlike the ICANN-approved top level domains, they are not fully regulated and are not recognizable by all servers.
A domain name may also have a “country code top level domain” (ccTLD) as a component. For example, “au” signifies Australia, and “uk” signifies the United Kingdom. Although most countries maintain their own country code registries, others have entered into agreements with corporations who want to market a particular country code domain. For example, the DotTV Corporation has entered into an agreement with the small nation of Tuvalu to take over the registry services for its “tv” country code domain. As a result, many United States businesses, including Motorola and Major League Baseball, now have their trademarks or trade names registered as “tv” domain names (e.g., www.motorola.tv). There are now more than 240 country code top level domains, and each country has different procedures and requirements for registration. For a list of the current country code domains and links to their registries, visit http://www.iana.org/cctld/cctld-whois.htm.
The “second level” is the main part of a domain name, and is sometimes referred to as the “domain name” in common usage. Typically, it is the second level domain that corresponds to the company’s name or best-known trademark, or a description of its business. For example, second-level domains include “IBM” in the Universal Resource Locator (URL) “http://www.ibm.com,” and “microsoft” in the URL “http://www.microsoft.com.”