1906
The AP institutes the FLASH:

"News matter of supreme importance which would necessitate the issuance of extra editions should be sent first as a 'flash' in a message not to exceed ten words, and should go upon all leased wires. Such "flash" must take precedence of all bulletins, must go upon each wire of a double or triple wire system, must be sent instantly upon the development of the news, and must never exceed ten words in length."

The last FLASH transmitted was when Neil Armstrong stepped on the moon.

In the days when it took several minutes to transmit or 'move' a story, a flash would break into the middle of anything that was currently moving.

These days as stories move in seconds, it is no longer necessary to use a flash to report important news.