A printed sheet containing one or more folds.
A folder is also a large sheet of heavy paper or paperboard which has been folded to form a pocket in which sheets can be filed and stored.
The term folder is also used to refer to the file organization system on a Macintosh computer or other window-based operating system. Computer files on any computer are stored in sets of hierarchical directories which, on GUI-based systems, use icons representing file folders as directories. The folder is intended to perpetuate the "desktop" metaphor common to the Macintosh and other similar systems.