Berlin, Germany

100 years ago today, “SOS” became effective as the worldwide standard for the International Morse code distress signal (· · · — — — · · ·) when it was included in the second International Radiotelegraphic Convention (which was signed on November 3, 1906, and took effect on July 1, 1908). This distress signal was first adopted by the German government in radio regulations effective April 1, 1905, and SOS remained the maritime distress signal until 1999, when it was replaced by the Global Maritime Distress and Safety System.

From the beginning, the SOS distress signal has actually consisted of a continuous sequence of three-dits/three-dahs/three-dits, all run together without letter spacing. In International Morse Code, three dits form the letter S, and three dahs make the letter O, so “SOS” became an easy way to remember the correct order of the dits and dashes. In popular usage, SOS became associated with phrases such as “Save Our Ship” or “Save Our Souls,” though by some accounts, “these phrases were a later development, most likely used to help remember the correct letters (something known as a backronym).”

Hmmm… backronym.