School bell sounds have long been used in videos as a shorthand for lessons starting or ending, and this short ringtone version became popular as creators looked for a clean, copyright free style alert they could also set on a phone. Online it spread through soundboards and short edits where a single ding sound effect style chime could mark a scene change instantly. Its appeal is simplicity: no voice or music, just a familiar institutional ring that audiences of any age recognise from their own school days and daily routines.