The strength of tones in music and the tones used in music are connected according to a certain relationship, and these tones form a system centered on one tone (tonic), which is the mode. Such as China's major mode, minor mode and pentatonic mode. The tones in the mode are arranged from the tonic to the highest tone to form a scale. The speed of music, the tune is also called melody. The ups and downs of music are organized horizontally and methodically according to a certain rhythm, forming a tune. Tune is the most important means of expression of music, and it is the essence and decisive factor of music.