URL

A Uniform Resource Locator (URL) specifies the Internet address of a file stored on a host computer connected to the Internet. Every file on the Internet, no matter what its access protocol (for example, HTTP or FTP), has a unique URL. Web software programs use the URL to retrieve the file from the host computer and directory in which the requested file resides. This file is then displayed in the client, most often the web browser.

NOTE

URLs are translated into IP addresses using the Internet DNS.

The format of a URL is as follows:

 protocol://host/path/filename 

For example, the URL for the meeting schedule of the House Committee on Agriculture of the U.S. House of Representatives can be found at the following address:

http://www.house.gov/agriculture/schedule.htm

The structure of this URL is as follows:

• Protocol: http

• Host computer name: www

• Second-level domain name: house

• Top-level domain name: gov

• Directory name: agriculture

• File name: schedule.htm

NOTE

The file extension .htm or .html indicates that the file is a HTML file.

Table 20-1 lists the top-level domains (TLDs) common in the United States.

Table 20-1. Top-Level Domains (TLD)^[*]

Domain Suffix	Domain Name
.com	Commercial Organization
.edu	Educational Institution
.gov	U.S. Government Organization
.mil	U.S. Military Organization
.net	Network Organizations (Access Providers)
.org	Nonprofit Organizations
.biz	Business Organizations[*]
.museum	Museums
.info	Unrestricted use[*]
.pro	Accountants, lawyers, physicians, and other professionals[*]
.name	For registration by individuals[*]
.aero	Air-transport industry
.coop	Cooperatives

^[*] Indicates TLD is unsponsored.

An "unsponsored" TLD operates under policies established by the global Internet community through the Internet Corporation for Assigned Names and Numbers (ICANN) process; a "sponsored" TLD is a specialized TLD that has a sponsor representing the narrower community that is most affected by the TLD. The sponsor carries out delegated policy-formulation responsibilities over many matters concerning the TLD.

NOTE

More information regarding the status of unsponsored TLDs can be found at http://www.icann.org/tlds/.