BSOD is an acronym for the semi-facetiously named “Blue Screen of Death”.
The BSOD is an error-reporting mechanism included in all versions of Windows. It presents a single screen full of information about a serious failure, and halts the computer completely – hence “death”. The information happens to be displayed as white text on a blue background – hence “blue screen”.
Windows attempts to handle errors transparently, safely, and without interrupting the normal operation of the system. Unfortunately, some errors are so disruptive to Windows’ own ability to operate that it simply can’t figure out what to do. The only thing it can do, as a kind of “last ditch effort”, is to halt the system, preventing possible damage and presenting the information about the failure in the infamous BSOD.
The information presented on a blue screen is in no way intended to be understood by the average computer user. Typically, Windows has found itself in such a state that it’s not safe for it try to analyze the error any further. It provides what amounts to highly technical information in the hopes that it can help a technician or someone versed in technical diagnosis.
In an ideal world, a BSOD would never, ever happen. In the real world, blue-screen incidents have been steadily decreasing with each successive version of Windows. The most common culprit for the BSOD today are poorly written drivers and hardware failure.