WiX is a declarative, open-source framework, originally created by Rob Mensching (http://blogs.msdn.com/robmen/default.aspx) The Wix team can be found at http://sourceforge.net/projects/wix/ and is Microsofts first open source team. WiX stands for Windows Installer XML, and is the most used piece of software at Microsoft.  But did you know that also MySQL and SugarCRM both use WiX to create Windows Installation Packages?