The FileBox is a user's personal library. It is a space-limited nook carved away by the administrator into which each user can place his or her private files. Although you can opt to share certain files that are in the FileBox with other users, by default these are hidden from everyone except the owner of the file and the administrator of the site.

The administrator, when editing the profile of a user, can set the maximum number of MB available in each user's FileBox. When that limit is reached, no more files may be added to that particular FileBox by that user. When the administrator sets the FileBox size to zero, the user effectively has no FileBox.

The FileBox differs from the Briefcase in that the Briefcase contains what you can consider 'shorcuts' to main library documents (not FileBox documents). To extend the metaphor, if you were to look inside the briefcase you would find notes about where to look in the library for a document not the actual document.  The FileBox on the other hand is an actual repository of documents distinct from the main library entirely. 

Administrators are able to quickly copy documents from a FileBox to the Library using the options at the bottom of the FileBox document list.