A password-protected directory is a folder which can't be accessed unless the proper login credentials are supplied. This could be an entire website or only one page that's located within a subfolder. If you try to open this type of a directory, you will see an Internet browser pop-up in which you have to type a username and also a password. If you enter the correct ones, you can continue surfing around the content without having to do anything else. If the login details aren't right, however, you will see a note that you are not authorized to see the content. In case this feature is active, you won't be able to open a file even when you have a direct link. The function is incredibly useful if you wish to restrict the access to some content or if you work on an Internet site and you don't want visitors to be able to access it prior to it being ready.