The document discusses opera roles and the different types of singers involved in opera productions. The principals are the main characters who are often guest artists, while the chorus includes twenty female and twenty male singers who either comment on or advance the story. The chorus is what makes opera special. A second document discusses the use of leitmotifs in romantic era operas to emphasize emotions. String and woodwind instruments are used. A third discusses opera as a combination of drama and music where dialogues and arias are sung. Significant opera composers through history are mentioned.