The Spotlight search service creates index databases of file system metadata so that it can perform normally time intensive searches nearly instantly. File system tags can be found in the Finder sidebar, Spotlight search, and any open or save document dialogs.

When fast user switching is enabled, all users are allowed to see other users' locally connected disks.

A user's home folder permissions can be reset from the Reset Password application on OS X Recovery.

Though Spotlight indexes file and folder permissions, it allows other users to search the contents of locally attached nonsystem volumes when ownership is ignored on those volumes.