If you are looking into this because you saw it mentioned in a specific community, it usually refers to:
Here is a short story exploring the mystery behind that file. The Archive at 4:04 AM
Elias froze. His own pulse thudded in his ears. He looked at his smart watch. 94bpm. Download 220USER txt
: A common motif where a seemingly boring text file contains "impossible" information about the reader.
The text at the bottom of the file began to overwrite itself, the characters flickering like dying neon. USER_220: Heart rate 105bpm. Status: Realizing. A new line appeared, one that wasn't there a second ago: ADMIN: Connection established. Hello, Elias. If you are looking into this because you
USER_001: Heart rate 72bpm. Location: Bedroom. Status: Sleeping.
Elias didn’t find the link; it found him. It appeared as a hyperlinked string of text in the metadata of an old MIDI file he’d downloaded from a defunct forum: . Curiosity, that old digital poison, took hold. He clicked. He looked at his smart watch
He realized with a cold shudder that the list was a real-time directory of people. He scrolled faster, the lines of text blurring into a rhythmic strobe of data. Finally, his eyes hit the bottom of the document.