(1) (.NET)  A software platform for developing applications from Microsoft.  See 
.NET Framework.
(2) (
.NETwork)  A top-level Internet domain used by carriers, ISPs and other communications-oriented organizations.  Both 
.net and 
.com domains are sometimes used by the same company.  However, the domain is not restricted, and anyone can register a 
.net domain, even if they have nothing to do with communications.  See 
Internet domain name.