High Quality Content by WIKIPEDIA articles! The origins of the break key on a computer keyboard go back to telegraph practices. A standard telegraph key has a built-in knife switch that can be used to short the key`s contacts. When the key was not in use, that switch was kept closed, so that a signal was continually sent. If that steady-state signal was interrupted, it indicated one of two things: either the operator was about to start transmitting, or something else had happened to break the connection—such as a physical break in the telegraph line.