This tone comes from Apple's iPhone, where a short alert for incoming messages became part of everyday phone use for millions of owners. Because the sound is heard constantly in real life, it travelled naturally into online video, where creators use it as shorthand for a text arriving, a reply landing or a secret being revealed. Its brevity and familiarity keep it useful across pranks, skits, reaction videos and edits, and it still works because almost everyone recognises it instantly without needing any explanation on screen.