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?

Every computer that hosts data on the Internet has 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 developed. 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.

In general, the three-letter domain name suffix* is known as a generic top-level domain and describes the type of organization. In the last few years, the lines have somewhat blurred* between these categories.
.com - business (commercial)
.edu - educational
.org - non-profit
.mil - military
.net - network provider
.gov - government

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

If a domain name is available, and provided it does not infringe* on an existing trademark, anyone can register the name for $35 a year through Network Solutions, Inc., which is authorized to register .com, .net and .org domains. You can use the box below to see if a name is a available. Don't be surprised if the .com name you want is already taken, however. Of the over 8 million domain names, 85% are .com domains.

ICANN, the Internet Corporation for Assigned Names and Numbers, manages the Domain Name System. As of this writing, there are plans to add additional top-level domains, such as .web and .store. When that will actually happen is anybody's guess.

To check for, or register a domain name, type it into the search box.
It should take this form: myname.com  

In addition to the generic top-level domains, 244 national top-level domains were established for countries and territories*, for example:

.au - Australia
.ca - Canada
.fr - France
.de - Germany
.uk - United Kingdom

For US $275 per name, you can also register an international domain name with Net Names. Be aware that some countries have restrictions for registering names.

If you plan to register your own domain name, whether it's a .com or not, keep these tips in mind:

The shorter the name, the better. (But it should reflect your family name, interest or business.)
The name should be easy to remember.
It should be easy to type without making mistakes.
Remember, the Internet is global. Ideally, a domain name will "read" in a language other than English.

　　注释：
　　Domain Name System：域名系统
　　infranstructure：下部结构，基础下部组织
　　correlate： 使相互关联，和…相关
　　suffix：后缀
　　blur： 把（界线）弄得模糊不清
　　infringe：破坏，侵犯，违反
　　territories：领土，版图，地域