Music notation is divided into simple notation, five-line notation and six-line notation. For example, the guitar uses six-line notation. In music theory, a whole note is four beats, a half note is two beats, a quarter note is one beat, an eighth note is 0.5 beats, a sixteenth note is 0.25 beats, etc. If a piece of music or a song has 1= on it C 4/4 (four quarters), "=110, that means this song is in the key of C in four-four beats (played with quarter note duration, four beats per measure), 110 beats per minute, if It is 1=G 6/8 (six eighths), "=90, which means that this song is in the key of G in eighty-six beats (played with eighth notes, six beats per measure), ninety per minute shoot. There is usually a simplified notation below the six-line notation, with a short section between the two vertical lines.