Hidden folders can help admins hide work in progress or admin-only materials to avoid overwhelming end-users with material that they do not need to see.
For example, if an admin creates a separate folder to hold information displayed in multiple end-user folders, each for a different team, the admin may wish to hide this source folder. The material (perhaps a list or wiki) in a hidden folder is then only visible to users in the folders where it is used.
Create a Hidden Folder
Folders whose names begin with "." or "_" are automatically hidden from non-admins in the navigation tree.
Note that the folder will still be visible in the navigation tree if it has non-hidden subfolders (i.e., folders where the user has read permissions). If an admin wishes to hide subfolders of a hidden folder, he/she can prefix the names of these subfolders with a dot or underscore as well.
Hiding a folder only affects its visibility in the navigation tree, not permissions to the folder. If a user is linked to the folder or enters the URL directly, the user will be able to see and use the folder based on permission settings regardless of the "hidden" nature.