Music

In Western musical notation, the staff or stave is a set of five horizontal lines and four spaces that each represent a different musical pitch or in the case of a percussion staff, different percussion instruments.

A clef is a musical symbol used to indicate which notes are represented by the lines and spaces on a musical stave. When a clef is placed on a stave it assigns a particular note to one of the five lines. This line becomes a reference point by which the names of the other notes on the stave are determined.

In Western musical notation, a key signature is a set of sharp, flat, or rarely, natural symbols placed on the staff at the beginning of a section of music. The initial key signature in a piece is placed immediately after the clef at the beginning of the first line. 

The time signature is a notational convention used in Western musical notation to specify how many beats are contained in each measure, and which note value is equivalent to a beat.

In music, a note is a symbol denoting a musical sound. In English usage a note is also the sound itself. Notes can represent the pitch and duration of a sound in musical notation. A note can also represent a pitch class.