.PSM1 File Extension
File TypeWindows PowerShell Script Module File
What is a PSM1 file?
Script used by Windows PowerShell, a program similar to the Windows Command Prompt that provides more advanced shell functionality; contains functions and variables that can be included as a single module in a separate .PS1 script; used for storing reusable PowerShell libraries.
PSD1 files are often included as part of module manifests, which are stored in .PSD1 files.