Final answer:
Hidden files are files that begin with a '.', and this naming convention is used in Unix-like systems to keep important files from being altered accidentally. They are not limited to superuser access and can be revealed with specific commands.
Step-by-step explanation:
Hidden files in computing are usually designated by a specific naming convention rather than permissions. The correct answer to what hidden files are is option 3) Files that begin with a '.'. This naming convention is primarily used in Unix-like operating systems such as Linux and macOS, where files and directories that start with a '.' (dot) are hidden from normal directory views. For example, .bashrc or .git are common hidden files. It is a simple way to help keep important configuration files and directories from being accidentally altered or deleted by users. These files are not necessarily only accessible to superusers, as users with the appropriate permissions can view and edit them by using commands or options that reveal hidden files, such as the 'ls -a' command in Linux.