Norma is an Italian opera in two acts. The music was composed by Vincenzo Bellini. The libretto is by Felice Romani.The opera was first performed at La Scala in Milan, on December 26, 1831. The work was based on Louis Alexandre Soumet's play "Norma ou l'infanticide". "Norma" is Bellini's masterpiece and one of the finest bel canto operas. The title role is one of the most demanding in the entire Italian repertoire. Sopranos Maria Callas, Joan Sutherland, and Montserrat Caballé have been amongst the best exponents of the role. 