Notating and Naming Pitches
Different pitches are indicated in musical notation by moving notes up and down on the staff (five horizontal lines). The higher the note, the higher it is placed on the staff.
When an instrument can play a very wide range of pitches (like a piano), it requires two staves, or a grand staff. At the far left of the two staves are two different clefs - on top is a treble clef, and on the bottom is a bass clef. Clefs tell us the range of pitches that can be represented on the staff lines. A treble clef is used for high pitches and a bass clef is used for low pitches.
two octaves of the C major scale on the grand staff
Middle C falls between the treble and bass clefs. It can be notated above the bass clef or below the treble clef on its own little line, a ledger line. Ledger lines can be used for pitches that fall above or below the staff, but notes on ledger lines can be more difficult to read than notes within the staff, so it is best to use the clef that allows the majority of pitches to be notated within the staff.
Middle C is also used as a reference point to compare the highness or lowness of other pitches. Middle C falls in the middle of a piano keyboard, and is towards the bottom range of a high female voice (a soprano), and in the upper range of a low male voice (a bass). See the page on voices for more on voice parts.
For instruments with smaller ranges, a single staff with one clef is sufficient. Lower instruments that tend to play below middle C (like the cello or tuba) will use the bass clef, while higher instruments that usually play above middle C (like the flute or violin) will use the treble clef.