Amidst a politically tumultuous world, a new style of jazz broke away from the constraints of mainstream modern jazz. Known as free jazz, this new style formed the core of the avant-garde movement in jazz. In this section, we will examine some influential avant-garde and free jazz musicians, and the artistic and cultural significance of their music. In addition, we'll consider the music of Miles Davis' mid-60s quintet, along with the significant individual contributions of the quintet’s pianist, Herbie Hancock.