Server files repository
From Carleton Moodle Docs
What are server files?
The server files repository enables teachers and managers to access files used within a course and elsewhere on the site which they have permission to access.
Activity modules for which files are available in the server files repository are:
A search box at the top of the Server files screen allows those users with relevant permissions elsewhere on the site to search other courses for a required file. A teacher who teaches several courses for example can now quickly locate a document used in one of her older courses by typing its name into the Search field.
When a file from the server files repository is re-used elsewhere on Moodle, the teacher has the option to make a copy (a new, unconnected version) or to create a shortcut or alias. See Working with files for more details.