A bracelet that finds the family when two million pilgrims move at once
During Hajj, the world's largest annual gathering of people in one place, every pilgrim wears a QR-coded silicone bracelet carrying nationality, accommodation tent, spoken language, and emergency contact. Pilgrims get separated in the Plain of Arafat and the tunnels of Mina; with two million people in a few square kilometres, they always will. Any volunteer with a phone can scan a bracelet and start the reunion. Finding the lost here is a problem older than the religion itself, and the bracelet is the current answer to it.