Folder

noun

1. An organizer that papers are kept in, usually with an index tab, to be stored as a single unit in a filing cabinet.

   "I keep all my schoolwork in a yellow folder."

2. A virtual container in a computer's file system, in which files and other folders may be stored. The files and subfolders in a folder are usually related.

   "My essays are in the folder named "Essays"."

3. A machine or person that folds things.
4. A folding knife.