Bharatanatyam contains different types of bani. Bani, or "tradition", is a term used to describe the dance technique and style specific to a guru or school, often named for the village of the guru. Bharatanatyam style is noted for its fixed upper torso, bent legs, and flexed knees (Aramandi) combined with footwork, and a vocabulary of sign language based on gestures of hands, eyes, and face muscles.[7] The dance is accompanied by music and a singer, and typically the dancer's guru is present as the nattuvanar or director-conductor of the performance and art. The performance repertoire of Bharatanatyam, like other classical dances, includes nrita (pure dance), nritya (Conveys a meaning to the audience through hand gestures) and natya (Consists of the elements of drama).[9][10] A program of bharatanatyam usually lasts two hours without interruption and includes a specific list of procedures, all performed by one dancer, who does not leave the stage or change costume. The accompanying orchestra—composed of drums, drone, and singer—occupies the back of the stage, led by the guru, or the teacher, of the dancer.