تعریف و معنای "ledger line"

What is a "ledger line"?

A ledger line is a short, horizontal line added above or below the staff to extend its range and indicate notes that are too high or too low to be written on the standard five lines. For example, if a note is higher than the top line of the staff, it will be placed on a ledger line above the staff. Similarly, notes lower than the bottom line are written on ledger lines below the staff. Ledger lines help musicians read and play notes that fall outside the regular staff range, ensuring that all pitches can be accurately notated.