What are Merge Module projects?

Merge Module projects enable you to install and deploy components consistently. Merge Module projects ensure that the correct version of a component is installed on the target computer. A Merge Module project contains a component such as a DLL along with dependent files, resources, registry entries, and setup logic. You cannot install merge modules directly. The modules are merged with an .msi file for each application that uses the component. This ensures that the component is installed consistently for all applications, eliminating problems such as version conflicts, missing registry entries, and improperly installed files. A merge module contains unique version information that the Windows Installer database uses to determine which applications can use the component, preventing the premature removal of a component. Therefore, a new merge module is created for every incremental version of a component. You should not update a merge module after including the module in an installer. The deployment tools in Visual Studio .NET make it easy to create Merge Modules and include them in installers for your applications.