Domain Names

When you think of the Internet, you probably think of “.com.” Just what do those three letters at the end of a World Wide Web address mean?

In order to locate online data, the servers that host the information each have a unique numerical address. For example, the numerical address for the White House is 198.137.240.100. But since few people want to remember long strings of numbers, the Domain Name System (DNS) was invented. DNS, a critical part of the Internet’s technical infrastructure, correlates a numerical address to a word. To access the White House website, you could type its number into the address box of your web browser. But most people prefer to use “www.whitehouse.gov.” In this case, the domain name is whitehouse.gov.

The Structure of a Domain Name

A domain name always has two or more parts separated by dots and typically consists of some form of an organization’s name and a three letter or more suffix. For example, the domain name for IBM is “ibm.com;” the United Nations is “un.org.”

The domain name suffix is known as a generic top-level domain (gTLD) and it describes the type of organization. However in the last few years, the lines have blurred somewhat between these categories. Currently in use of these gTLDs:

.aero: for the air-transport industry
.biz: reserved for businesses
.com: for businesses, commercial enterprises, or online services like America Online. Most companies use this extension.
.coop: reserved for cooperatives
.edu: for educational institutions and universities
.gov: reserved for United States government agencies
.info: for all uses
.int: for organizations established by international treaties
.mil: for the United States military
.museum: for use by museums
.name: for use by individuals
.net: for networks; usually reserved for organizations such as Internet service providers
.org: for non-commercial organizations
.pro: for use by professionals, such as attorneys and physicians

ICANN, the Internet Corporation for Assigned Names and Numbers, manages the Domain Name System. For the latest news, visit the ICANN website. The more popular TLDs (.com, .net, .org, .biz, .info, .name) are available to the general public for registration of domain names and do not require an application.

Hosts

A host is any computer directly connected to a network that acts as a repository for services (such as e-mail, Usenet newsgroups, FTP, or World Wide Web) available for other computers on the network.