SOS is an urgent distress signal used when someone needs immediate help, especially at sea or in remote areas. The three letters don't actually stand for anything. They were chosen in 1905 because in Morse code (dot-dot-dot, dash-dash-dash, dot-dot-dot), they create a distinctive pattern that's easy to recognize and hard to confuse with other messages, even through static or poor radio conditions.

When a ship is sinking, when someone is stranded on a mountain, or when an aircraft has an emergency, sending an SOS means “we need rescue right now.” Before radios, ships would fire flares or wave flags to signal distress. Today, pressing an SOS button on an emergency beacon can send your location to rescue services via satellite.

You'll sometimes hear people use SOS more casually, like saying “I need to send out an SOS for help with my science project,” but the real SOS is reserved for genuine emergencies. When rescuers receive an SOS, they drop everything to respond, because they know someone's life might depend on it. That's why the signal must never be used as a joke or a false alarm.