A "system folder" refers to a specific location on a computer or electronic device where important files and data needed for the operating system to function properly are stored. Full definition
They are system folders which play an important role. (thewindowsclub.com)
It was a clever and neat way to get some things done, like run games in your high school computer lab when you couldn't open system folders or create shortcuts. (howtogeek.com)
You can order either a two or three - person rear seat layout, and the rear seat system folds down to carry extra luggage. (bmwblog.com)