- .com represents the word "commercial," and is the most widely used extension in the world. Most businesses prefer a .com domain name because it is a highly recognized symbol for having a business presence on the Internet.
- .net represents the word "network," and is most commonly used by Internet service providers, Web-hosting companies or other businesses that are directly involved in the infrastructure of the Internet. Additionally, some businesses choose domain names with a .net extension for their intranet Websites.
- .org represents the word "organization," and is primarily used by non-profits groups or trade associations.
- .biz is used for small business Web sites.
- .info is for credible resource Web sites and signifies a "resource" web site. It's the most popular extension beyond .com, .net and .org.
- .mobi (short for "mobile") is reserved for Web sites built for easy viewing on mobile devices.
- .us is for American Web sites and is the newest extension. It has the largest amount of available names in inventory.
- .cc was originally the country code for Coco's Keeling Islands. It is unrestricted and may be registered by anyone, from any country.
- .bz was originally designated as the country code for Belize, but is now commonly used by small business who can't get the name they want using the .biz extension. It is unrestricted and may be registered by anyone, from any country.
- .tv is for rich content/multi-media Web sites, commonly used within the entertainment or media industry.
- .vg is the country code for the British Virgin Islands. It is unrestricted and may be registered by anyone, from any country.
- .ws was originally designated as the country code for Western Samoa, but is now commonly used as an acronym for "Web sites." It is unrestricted and may be registered by anyone, from any country.
- .name is the only domain extension specifically designed for personal use. It is commonly used for easy to remember e-mail addresses and personal web sites that display photos or personal information about an individual.
- .co.uk is the country code for United Kingdom. The .co portion of the extension indicates the domain name is for commercial purposes (similar to a standard .com extension). It is unrestricted and may be registered by anyone, from any country.
- .org.uk is the country code for United Kingdom. The .org portion of the extension indicates the domain name is for an organization. It is unrestricted.
for more visit: http://en.wikipedia.org/wiki/List_of_Internet_top-level_domains
