A file with a special hidden attribute turned on, so that the file is not normally visible to users. For example, hidden files are not listed when you execute the DOS DIR command. However, most file management utilities allow you to view hidden files.
DOS hides some files, such as MSDOS.SYS and IO.SYS, so that you will not accidentally corrupt them. You can also turn on the hidden attribute for any normal file, thereby making it invisible to casual snoopers. On a Macintosh, you can hide files with the ResEdit utility.