The Book of Songs is originally a musical song, which can be sung by music. According to different music, it can be divided into wind, elegance and ode.
"Wind" is the national wind, which is the music of various vassal States and places in the Zhou Dynasty, mostly folk songs.
Those "elegant" people are also right. What the Zhou people thought of as "correct pronunciation" was the elegant music directly under the jurisdiction of the Zhou Dynasty. There are big and small elegance. A few of Er Ya are folk songs, and most of them are works of noble literati.
"Ode" is an ode to the temple, and it is the music that the nobles worship the gods and ancestors. Ode is divided into three parts: Zhou Song, Truffle and Shang Ode.