A PowerShell module is a conjoined portion of PowerShell functions or grouped code. All PowerShell CMDLETS and providers are incorporated by a module or a snap-in. The receivers of these modules can add the commands included in the module to their PowerShell sessions to use them like built-in commands. The most uncomplicated method to build a PowerShell module is to save the SCRIPT as a PSM1 file. 

A PowerShell module includes 4 fundamental elements:

• A PSM file, being the module;
• Help files or scripts required by the module;
• A manifest file that defines the module
• A directory that accumulates the content.

There are four TYPES of PowerShell modules:

• Script module: A PSM1 file that includes different functions to allow admins to execute management functions, IMPORT, and export.
• Binary module: A .NET framework assembly (DLL file) that includes saved code. Programmers generally utilize a binary module to build cmdlets with strong features not easily done with a PowerShell script.
• Manifest module: A module (PSM1) file with an associated PSD1 file (manifest).
• Dynamic module: A dynamic module is dynamically built on demand by a script. It isn't reserved or loaded to persistent storage.