This ballet style is often performed barefoot. Contemporary ballets may include mime and acting, and are usually set to music (typically orchestral but occasionally vocal). It can be difficult to differentiate this form from neoclassical or modern ballet. Contemporary ballet is also close to contemporary dance because many contemporary ballet concepts come from the ideas and innovations of twentieth-century modern dance, including floor work and turn-in of the legs. The main distinction is that ballet technique is essential to perform a contemporary ballet.