The role of Light.exe

If you've added a .wxl file to your WiX project in Visual Studio, or maybe several .wxl files—perhaps en-us.wxl for English and es-es.wxl for Spanish—building the project will create an installer for each one. They'll be stored in the bin folder under separate subfolders. This is without declaring which languages you want to build for. By default, Visual Studio detects all of the languages you've added and creates an MSI for each one.

The commands used to build the MSIs are the same that you learned about in Chapter 9, Working from the Command Line. First, Visual Studio calls Candle to compile the .wxs source code files into .wixobj object files. Then, it makes a distinct call to Light for each .wxl file, passing the -loc and -cultures flags. The following is the build process, truncated and formatted for readability:

Candle.exe -out obj\Debug\ -arch x86 Product.wxs

Light.exe -out "bin\Debug\en-us\MyInstaller.msi" 
   -cultures:en-us 
   -loc en-us.wxl 
   -loc es-es...