Control-Alt-Delete
Bradley did not intend Control-Alt-Delete to be used by end users — it was meant to be used by people writing programs or documentation, so that they could reboot their computers without powering them down. This was useful since after a computer was powered down, it was necessary to wait a few seconds before powering it up again to avoid potential damage to the power supply and hard drive. Since software developers and technical writers would need to restart a computer many times, this key combination was a big time-saver. Bradley chose this key combination because it is practically impossible to accidentally press this combination of keys on a standard keyboard. However, the key combination was revealed to the public when developers found it useful, and at the 20th anniversary of the IBM PC, while on a panel with Bill Gates, Bradley said "I may have invented it (control-alt-delete), but I think Bill made it famous".
Read more about this topic: David Bradley (engineer)