Folders enable you to group files together in a meaningful way. Folders can be designated as private, shared, or available to everyone.
You can create a folder to enable files to be grouped together. This enables you to group files together for yourself in a meaningful way. You can optionally enable one of three types of sharing capabilities to allow others to collaborate on files within the folder -- reader, contributor, or owner.
If you make a private folder public, files that are not assigned to be public are removed from the folder.
When you share a folder with people and communities, they can see the files in that folder. However, they cannot see those same files anywhere else unless you explicitly share the files with them. For example, if you add a file to a folder and share the folder with Cathy but have not shared the file with Cathy, she can see and open the file in the folder, but cannot see it in any other list.
When you share a folder with people or change their role, those people are notified.