Modules are a way of packaging and distributing Maya plug-ins.
Maya modules can include files such as scripts and icons in addition to the plug-in file. To create a module, the module directory is zipped and packaged into a module along with a module file that describes how the files are to be used on different platforms.
To create a module:
Create the icons, plug-ins, presets, and scripts subdirectories under your top-level module directory.
These are the default directories that Maya expects to find in a module. You can choose to use different directories or multiple directories in your module, but you will need to specify these in the module description file.
Create a module description file file with the .mod extension
Once your module directory is complete, compress it and the module description file together. This zipped file is your module file.