A password-protected directory is a folder which can't be accessed unless the right login credentials are provided. This can be a whole website or only one page that's located within a subfolder. If you attempt to open this type of a directory, you will see an Internet browser pop-up in which you must type in a username as well as a password. In case you enter the appropriate ones, you can continue surfing around the content without having to do anything more. If the login credentials aren't right, however, you will see information that you aren't allowed to look at the content. When this function is enabled, you won't be able to open a file even when you have a direct link. The function is quite practical if you'd like to restrict the access to some content or if you are developing an Internet site and you don't want visitors to be able to access it before it's ready.