The SOS distress signal has been a staple for emergency communication for over 100 years, and although communications technology is very different now to the days of Morse Code, the term is still widely used today.

The SOS distress signal was the work of the British Marconi Society and the German Telefunk, it was established as an International Distress Signal on October 3 1906 and was introduced on July 1, 1908.

[Read more: From Pan Pan to SOS - 9 things you didn't know about the history of the distress signal]

To celebrate this landmark occasion, we take a look at some of the interesting SOS facts from across the last 109 years:

SOS does not stand for anything

Contrary to popular belief, SOS does not stand for ‘save our souls’ or ‘save our ship’. Nor does it mean ‘send out succour’. SOS actually stands for nothing at all.

SOS was selected purely because it could be very easily transmitted in Morse code during distress · · · – – – · · · (dot-dot-dot, dash-dash-dash, dot-dot-dot). Only later did the likes of ‘save our souls’ emerge.

The SOS signal was first used in 1909

SOS was formally introduced on July 1, 1908 and almost a year later it was used by the Cunard liner SS Slavonia on July 10, 1909 during a shipwreck off the Azores, Portugal.

All on board were rescued, and some of the cargo – which included 400 bags of coffee, 1,000 ingots of copper and 200 casks of oil – were salvaged from the wreckage before it was completely abandoned.

SOS took a while to be adopted

Even though the SOS distress signal was made official in 1908, it took some time to be widely adopted. So much so that in 1912, the radio operator aboard the striken Titanic used the old CQD distress signal first before he joked that they may as well do the new SOS distress signal too as they may never get a chance to try it again.

SOS was almost SOE

At the conference in Berlin to establish a universal distress, signal countries clubbed together to pitch their ideas.  While the UK used CQD, the Italians used SSSDDD, while the Germans had SOE.

However, the final E represented one dot, and many agreed it could be easily missed. And so, the E was replaced with an S.

SOS was replaced in 1999

Countries began decommissioning Morse equipment on board ships from 1992, and in 1999 a new satellite-based system (known as the Global Maritime Distress and Safety System) for sending distress signals at sea was fully introduced.

Think you know Morse code? Try our quiz.

Do you know any facts about SOS? Let us know in the Comments section below.

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