Sheet music symbols are used to indicate how a piece of music should be played. The most common symbols are the REST, CLEF, segno, and gclef. A REST is a symbol that indicates a pause in the music. A CLEF is a symbol that indicates the pitch of the notes on the staff. A segno is a symbol that indicates a return to a previous section of the music. Finally, a gclef is a symbol that indicates the pitch of the notes on the treble staff.