@harmonyval creatively explains the use of ledger lines in music. Did you know that before this modern notation, there were more than 5 lines per stave? It would be a nightmare trying to figure out what note you had to play! When a note goes above the stave, we have to use what we call 'ledger lines' to indicate where a line would have been otherwise. If we did not use ledger lines, we wouldn't be able to accurately determine what note it was.
