Welcome, this is Terry Ewell and this is your video on ledger lines. I like to think of ledger lines as being ladders. These are extensions above and below the staff. Here we have the piano grand staff: the treble clef, a brace connecting the two staves. Here is the treble clef, the bass clef, the staff, and a bar.
So a ledger line goes above or below. Here I have a note. You can see that Finale automatically adds a ledger line. Here is an F, a G, and then if I want to go one above it, there is an A. If I wanted to go two above that. There is a C. Notice that the C has two ledger lines. See those two ledger lines there. Here is the A with a single ledger line.
Now the ledger lines are not drawn all the way across like a whole line. Rather they are added like little ladders for each note.
Now the interesting thing about these two staves is that if I go one ledger line down I get a middle C. (Oh, I have to erase these two rests here.) I go one ledger line down, I get a middle C. If I go one ledger line above the bass staff, I also get a middle C. So although these two notes look very different on the staff (music), they actually play the same note on the piano.
Well, the lowest line on the bass clef is a G. if I add ledger lines down below, here is an E. Going down is a low C. Going down even further is a low A. You can see how those ledger lines are added.
So that is your brief introduction on ledger lines. I hope that this has been helpful for you to understand how they work.