What and When Dot Net ?

We all are very much aware with Dot Net (Microsoft) Technology but do we really know why and when it came in to the picture.
The starting version of Dot Net is based on Java langaugae and further Dot Net versions came with more extended functionalities. Java is a plateform independent language because of its compilation in byte code. Same Dot Net is made language independent using CLR (Common Language Runtime). The code will be compiled in to MSIL (Microsoft Intermediate Language) and then further conveted into machine language by Just In Time compiler (part of CLR). Dot Net is less a programming language and more of a framework for developing applications. Any language that can be build to target the CLR (Common Language Runtime) can be considered a "Dot Net" language. Examples include C#, VB.Net, IronRuby, IronPython, and F#.
I collected some data about Dot Net versions from wikipedia:

Version - 1.0
Version Number - 1.0.3705.0
Release Date - 2002-02-13
Visual Studio .NET
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Version - 1.1
Version Number - 1.1.4322.573
Release Date - 2003-04-24
Visual Studio .NET 2003
Operating System - Windows Server 2003
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Version - 2.0
Version Number - 2.0.50727.42
Release Date - 2005-11-07
Visual Studio 2005
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Version - 3.0
Version Number - 3.0.4506.30
Release Date - 2006-11-06
Operating System - Windows Vista, Windows Server 2008
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Version - 3.5
Version Number - 3.5.21022.8
Release Date - 2007-11-19
Visual Studio 2008
Operating System - Windows 7, Windows Server 2008 R2
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Version - 4.0 Beta 1
Release Date - 2009-05-20
Visual Studio 2010