Source : Free On-Line Dictionary of Computing

.NET framework
     
         A software development and execution
        environment designed by {Microsoft} as a direct competitor to
        {Java}.  .NET framework should not be confused with
        {Microsoft}'s past labeling of a line of products as ".NET".
     
        .NET simplifies interoperability between languages and
        machines on {Microsoft Windows} especially, although not
        specifically, for web based services.  Essentially the .NET
        framework consists of the CLR (common language runtime), CTS
        (common type system), CLS (common language system), and IL
        (intermediate language).
     
        The CLR consists of a number of resources provided to .NET
        applications such as the security model, type system and .NET
        classes (c.f. Java classes).  The CTS is the range of all
        types that .NET understands although it is not necessarily the
        case that a .NET program will understand all of these types.
        The CLS however is a subset of the CTS which all .NET
        languages must support: any two .NET languages can
        interoperate via. the CLS.
     
        All .NET languages are at some stage compiled into the IL, a
        {byte-code} like language.  However unlike a standard Java run
        time environment, the IL is converted to {machine code} either
        upon installation of the software or at {run time} by a {just
        in time compiler} (JIT).  The IL is not interpretted.
     
        .NET's main weakness is that Microsoft have ignored the {Unix}
        and {mainframe} environments, effectively ruling .NET out of
        use in many {enterprise} environments.  However there is
        {Mono} - an {open source} .NET framework for Unix}.
     
        .NET was based on research by Steven Lucco on a product called
        {OmniVM}, sold by {Colusa software}.  Attracted to OmniVM
        since VB and C/C++ environments were already available,
        Microsoft bought Colusa in 1996.  Microsoft provides .NET
        compilers for {C#}, {C++}, {VB}, and {Jscript}.
     
        (2003-09-24)