What does SOS mean? Since they are all capitalized, is it an abbreviation form?

Native speaker’s answer
Rebecca
Some people believe that "SOS" stands for "Save Our Ship" or "Save Our Souls," but there is no evidence to prove this. "SOS" is a three-digit Morse code ("S" "O" "S") that was originally used by sailors in the early twentieth century when they ran into trouble. Now, it has become a universal code or signal used by people requiring emergency assistance. It is also used informally to mean "help." Ex: The ship just sent out an SOS signal. They need immediate assistance. Ex: My classmate sent me a silent SOS with his eyes. He needed help with his homework.