Internet Explorer Document Modes

Interoperable HTML5 Quirks Mode in IE10
http://blogs.msdn.com/b/ie/archive/2011/12/14/interoperable-html5-quirks-mode-in-ie10.aspx

Activating Browser Modes with Doctype
http://hsivonen.iki.fi/doctype/#ie8

Compatibility View and "Smart Defaults"
http://blogs.msdn.com/b/ie/archive/2009/06/17/compatibility-view-and-smart-defaults.aspx

META Tags and Locking in Future Compatibility
http://msdn.microsoft.com/en-us/library/cc817574.aspx

MSDN: Defining document compatibility
http://msdn.microsoft.com/en-us/library/cc288325%28v=vs.85%29.aspx
"If Internet Explorer encounters a webpage that doesn't contain a <!DOCTYPE> element, it opens the page in quirks mode, which can lead to several unexpected side-effects if you're unfamiliar with the directive. For more info, see How to Enable Standards Support."

MSDN: Specifying legacy document modes
http://msdn.microsoft.com/en-us/library/jj676915%28v=vs.85%29.aspx
"Note  As of Internet Explorer 10, quirks mode behaves differently than it did in earlier versions of the browser. In Windows Internet Explorer 9 and earlier versions, quirks mode restricted the webpage to the features supported by Microsoft Internet Explorer 5.5. In Internet Explorer 10, quirks mode conforms to the differences specified in the HTML5 specification. For more info, see Specifying legacy document modes."

MSDN: document.documentMode property (Internet Explorer)
http://msdn.microsoft.com/en-us/library/ie/cc196988%28v=vs.85%29.aspx

MSDN: document.compatMode property (Internet Explorer)
http://msdn.microsoft.com/en-us/library/ie/ms533687%28v=vs.85%29.aspx

Internet Explorer 8 document and browser modes
http://www.nczonline.net/blog/2010/01/19/internet-explorer-8-document-and-browser-modes/

Testing sites with Browser Mode vs. Doc Mode
http://blogs.msdn.com/b/ie/archive/2010/10/19/testing-sites-with-browser-mode-vs-doc-mode.aspx