Leonard Bernstein's "Candide" is an operetta. An operetta is like an opera, with one big difference. In opera, everything is sung, but in operetta, there are spoken lines between the singing. Composers who wrote operettas in English include Sir Arthur Sullivan (who can't be separated from William S. Gilbert, who wrote the words for Gilbert and Sullivan operettas), Victor Herbert, Sigmund Romberg, and Rudolf Friml.