.PSC File Extension
File TypePapyrus Script
What is a PSC file?
Source code file written in the Papyrus language; used to create a plugin for The Elder Scrolls V: Skyrim; contains functions that define events that occur in the game, such as a message or the behavior of a character.
Once you create your PSC file, place it in the Data/Scripts/Source location in your Skyrim installation directory. You can then compile the script and create a plugin by loading the appropriate .ESM file(s) in Creation Kit.