It was adopted globally as the recognised distress signal for ships at sea exactly a century ago on July 1, 1908. Until then, the most commonly used signal was the "CQD", which held the danger of being interpreted differently. After a lot of discussions, the 'SOS', which consisted of three dots, three dashes and three more dots was selected, reports Times Online.
The signal's success began a year later in 1909 when the Cunard liner the SS Slavonia was stricken off the Azores, and sent out an SOS signal. Tragedy was averted and no life was lost.
However, some ships and boats continued to use the CQD.
The need for a universal code was eventually recognised with the tragedy of the Titanic in April 1912.
After the ship hit an iceberg, its radio operators sent out both the old CQD and the new SOS signals.
However, ships in the area ignored both thinking the Titanic was having a party. It was only after the loss of lives measured up to 1,500 that the new SOS distress signal was rarely ignored.