isr.co.ro : glossary Folder In the file-directory system for graphical operating systems such as Macintosh and Windows, the visual representation of a subdirectory. Folders serve primarily as a convenience for the user by making it easier to locate files, but they can also tell a program where to look for supporting files or data. Similarly, in many application programs, a container for holding documents, messages, or bookmarks. For example, many e-mail programs place incoming messages into an inbox folder.