In many computeroperating systems, a special type of error message will display onscreen when the system has experienced a fatal error. Computer users have dubbed these messages screens of death as they typically result in unsaved work being lost and often indicate serious problems with the system's hardware or software. Screens of death are usually the result of a kernel panic, although the terms are frequently used interchangeably. Most screens of death are displayed on an even background color with a message advising the user to restart the computer.
A kernel panic is used primarily by Unix and Unix-like operating systems: the Unix equivalent of Microsoft's Blue Screen of Death. It is used to describe a fatal error from which the operating system cannot recover.
A Sad Mac is a symbol used by older-generation Apple Macintosh computers, starting with the original Macintosh 128K, to indicate a severe hardware or software problem that prevented startup from occurring successfully. A similar symbol exists for the iPod.