http://en.wikipedia.org/wiki/.net

The domain name net is a generic top-level domain (gTLD) used in the Domain Name System of theInternet. The name is derived from network, indicating its originally intended purpose was for organizations involved in networking technologies, such as Internet service providers and other infrastructure companies. However, restrictions were never enforced and the domain is now a general purpose name space. It is still popular with network operators, and is often treated as an alternative to com.

net is one of the original top-level domains[1] (the other five being com, edu, gov, mil, and org) despite not being mentioned in RFC 920, having been created in January 1985. As of 2011, it is the third most popular top-level domain, after .com and .de.[2]