in harmony, the first to seventh grades are written as: first grade (c), second grade (d), third grade (e), fourth grade (f), fifth grade (g), sixth grade (a) and seventh grade (b).

In music theory, harmony is an important element in music creation. By combining different notes together, a pleasant melody is formed. Each level of harmony has its specific interval and function. For example, the first level (tonic) is the stable foundation of music, while the seventh level (leading tone) tends to lead to the first level, making music coherent.

In the specific music creation, the use of harmony needs to be reasonably matched according to the style, tonality, rhythm and other factors of music, so as to enhance the expressive force and emotional communication effect of music.