The Blue Screen of Death (also called BSoD, Blue Screen, or bluescreen) is the error screen displayed by the Microsoft Windows family of operating systems upon encountering a critical error, of a non-recoverable nature.
A Blue Screen of Death, abbreviated as BSOD, and officially called a Stop Error or Stop code in Microsoft, is a diagnostic screen characteristic of Microsoft Windows operating systems upon encountering a fatal critical error such that your computer can no longer operate safely. The only safe action in response to a BSOD is that you need to restart your computer.
A BSOD includes text indicates that a fatal problem has occurred on your PC, and that it can no longer operate safely without restarting. Information about a stop code is provided, either as a symbolic name (such as "CRITICAL_PROCESS_DIED") or a 8-digit hexadecimal error code (in this case, 0x000000EF). The below image depicts a sample Windows 10 BSOD with its sad emoticon and its stop code of "CRITICAL_PROCESS_DIED".
Blue Screen of Deaths and similar diagnostic screens (such as Black Screen of Death, Red Screen of Death, etc) are also used for similar reasons in other operating systems.
Official Microsoft link to BSOD Stop Codes: https://support.microsoft.com/en-gb/help/14238/windows-10-troubleshoot-blue-screen-errors
Wikipedia article: https://en.wikipedia.org/wiki/Blue_Screen_of_Death
