The Break key is a keyboard key whose original purpose was to immediately halt execution of a running a program. On modern computers, it has no default function. It is not commonly used, although any software may use it for its own purpose. The Break key may also be remapped with a program like AutoHotkey.
I use this all the time in my day to day. Except it’s Ctrl-C. Sometimes Ctrl-Z +
kill -9if it’s being extra ornery.