anyone using prism is probably familar with the bootstrapper, the documentation defines the bootstrapper as a class responsible for initialization of an application built using Prism and if you dig into the code for it you will see lots of virtual methods that you can override when setting up your application, one of those is the CreateModuleCatalog(). There are several ways to initialize your modules but using an xaml file is incredibly convenient especially if you only want certain parts of your application to load under certain conditions. Where I work we recently decided to employ this feature so that we could load a subset of the application in the warehouse and not have the sales and other modules loading up at run time, on the flip side the warehouse module doesn't load when the sales team loads the application. The great part for the developer is you don't end up with multiple code bases, your core and infrastructure is shared in one application and different people see...
Nerdy stuff - mostly about C# and the Microsoft stack.