CLR - Common Language Runtime

About Common Language Runtime
http://www.gotdotnet.com/team/clr/about_clr.aspx

NET Framework Developer's Guide - CLR
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconthecommonlanguageruntime.asp

Techinical Overview of CLR
http://research.microsoft.com/~emeijer/Papers/CLR.pdf