Details:
Originally, the three letter extensions, or Top Level Domains (TLDs), were meant 
to denote whether the domain name was being used for business (.com), non-
profit (.org), or for a technology based company (.net). 
However, with the explosion of the Internet (and specifically, the World Wide Web) 
as a new business medium, the lines were blurred, and companies and 
individuals alike started cross-registering domains (ie. domain.com, domain.net, 
domain.org) just to protect their interests. Now, .com, .net, and .org names (the 
generic Top Level Domains) can be used for any purpose.