Virtual file system
All files and folders that are served by HFS are configured in Admin > Shared files.
Initially, you only have the home element, and it's empty.
In the most simple configuration, you can configure the home/root to be linked to a real folder on your disk. All its content will then available. To do that we use the Load content from disk, and pick the folder we want. That's what it looks like before we set it:
The Virtual File System (VFS) can do much more than the simple use-case above. The name "virtual" implies that it can show things differently from what is actually on the disk. Whatever the administrator configures in the VFS is virtual, and this means no change is reflected on the disk.
The VFS is then made accesible in the user front-end, that you can see in this picture:
By default, no change is possible in the front-end, unless you give permissions explicitly. But if permissions are given, then the rule of thumb is that changes done in the front-end are done on disk. If you upload a file, that will be phisically placed in that folder, and a deleted folder is actually gone.
Summing up, a huge difference between operations in the Admin panel and the front-end is that the first will change the VFS, while the latter changes the disk content.