The international distress signal in Morse code is SOS, but it was never intended to be an acronym for anything. In fact, the three dots and three dashes was once internationally a code for S5S. The backronym "Save Our Ship" is useful when you are learning how to recognize it, so that phrase became a common explanation.
The telegraph and Morse code were developed in the 1840s, but the system was no use for ships at sea because it required wires. But then Marconi gave us a wireless telegraph system, or "radio," first demonstrated in 1896. Suddenly, communications from ships at sea was possible, but it took some time and some left turns to work out standard international codes. The most important was a distress signal, calling any available ships for immediate aid. For some time, this code was CQD. Simon Whistler of Today I Found Out explains how that got (slowly) turned into the SOS signal that we all recognize today, despite the fact that ships no longer use Morse code. -via Laughing Squid