Windows has some built-in "error-detection" software, in the style:
IF (some condition goes here) IS NOT "true" THEN (report an failure to "assert")
If everything is OK, then the condition will be "true".
If something has gone wrong, the "assertion" will be "false".
If you pick up a LEFT shoe, and put it on your LEFT foot, that is normal. If you pick up a LEFT shoe, and try to put it on your RIGHT foot, then you have a problem, even before you take one stop. The failure of the "assertion" that LEFT-to-LEFT is what you see is usually followed by a palm-slap to your forehead. :-)