A .netmodule file is a .NET Framework assembly that does not contain an assembly manifest. It's essentially a compiled code module, similar to a DLL (Dynamic Link Library), but without the metadata that defines the assembly's identity, dependencies, and other crucial information for deployment and execution. These modules are designed to be linked together at a later stage, typically using the Assembly Linker (al.exe) tool, to create a complete .NET assembly (either an executable .exe or a library .dll). This allows for modular development, where different parts of an application can be compiled separately and then combined. The .netmodule format is useful for scenarios where you want to break down a large project into smaller, manageable pieces, or when you need to share code between multiple assemblies without creating a strong dependency. It also facilitates incremental compilation, where only the modified modules need to be recompiled, speeding up the development process. The final assembly manifest is then created when all the modules are linked together, defining the overall structure and dependencies of the application.