The Blue Screen of Death (also called BSoD, Blue Screen, or bluescreen), known officially as a Stop Error or a bug check, is the error screen displayed by the Microsoft Windows family of operating systems upon encountering a critical error, of a non-recoverable nature, that causes the system to “crash.” The term is named after the color of the screen generated by the error. In UNIX-based operating systems, a similar term is kernel panic.
Stop errors are usually hardware or driver related, causing the computer to stop responding in order to prevent damage to the hardware, whereupon, in the latest versions of Windows, the screen presents information for diagnostic purposes that was collected as the operating system performed a bug check.
The term Blue Screen of Death originated during development of the IBM OS/2 operating system at Lattice Inc, the makers of early Windows and OS/2 compilers. Developers encountered the error screen when bugs in the operating system’s software (typically null pointers) slipped through the net during beta testing. In feedback to IBM, a company known informally as ‘Big Blue’, the developers humorously described the Stop screen as the ‘Blue Screen of Death’ in consequence of its color, of the association of that color with IBM, and of the finality of the error (which caused the computer to hang without any possibility of recovery, requiring a manual restart).