.com - commercial 
An open TLD - any person or entity is permitted to register. 
The .com TLD has been around longer than any other. It was originally intended for use by for-profit business entities, but it became the main and most popular TLD for domain names used by all types of entities. It implies a certain level of professionalism and longevity and is still considered the best choice for commercial entities with a global market presence.  
Google and other search engines tend to favour websites that use a .com domain name. This increases Search Engine Optimization (SEO) and the online visibility of the website and is one reason people choose a .com TLD for their business. However, it is often more costly and not always the most suitable choice for their brand or market.

.net – network organisations
 An open TLD - any person or entity is permitted to register. 
Typically these are internet infrastructure sites

.org – organisation 
An open TLD - any person or entity is permitted to register. 
The .org TLD is commonly associated with open-source projects, education, online communities, non-profits, or even for-profit institutions. It was originally intended for use by non-profit organizations, and still primarily used by some.       

.int - international organisations 
The .int TLD is strictly limited to organisations, offices, and programs endorsed by a treaty between two or more nations.

.edu – educational 
Restricted TLD used for educational institutions.
.gov - government agencies
 Restricted TLD

.mil – Military
Restricted TLD

In 2001 and 2002 seven more were introduced. Four of these - .biz, .info, .name, and .pro - are unsponsored. The other three - .aero, .coop, and .museum - are sponsored.
In 2003, six new sponsored TLDs were introduced - .asia, .cat, .jobs, .mobi, .tel and .travel