This term designates a series of horizontal parallel lines, upon and between which the notes are written. By looking at the clef, the pitch of every note can be easily identified.
Although today we are used to the five-line stave, more lines were used in earlier periods. In the organ music of Frescobaldi (1583-1643), for instance, we find a right-hand stave of six lines and a Left-hand staff of eight lines.
As you have surely noticed, Staff and Stave are synonymous.
