Mobile keypad sounds come from the touch-tone and click sounds built into early mobile phones, when every number press produced a distinct beep. As texting became a daily habit, that noise became a shorthand in films, television and online video for someone communicating by phone. Creators now use short recordings of it to suggest a message being written without showing the whole conversation, and its brevity makes it easy to drop into edits, memes and skits. The sound remains familiar because almost everyone recognises the rhythm of typing on a phone.