InstallWizard MSI Merge Modules

Merge modules provide a standard method by which developers deliver shared Windows® Installer components and setup logic to their applications. Merge modules are used to deliver shared code, files, resources, registry entries, and setup logic to applications as a single compound file.
When a merge module is merged into the .msi file of an application, all the information and resources required to install the components delivered by the merge module are incorporated into the application's .msi file.
Because all the information needed to install the components is delivered as a single file, the use of merge modules can eliminate many instances of version conflicts, missing registry entries, and improperly installed files.