Donald Young, age 15, of Nashville, Tenn., for his question:

EXACTLY WHAT IS A LIBRETTO?

A libretto is the text of an opera or other staged musical work. The term sometimes also refers to the text of an oratorio or to a ballet scenario.

In the libretto of a musical, the dialogue is called the book and the song words, the lyrics.

A successful libretto must be effective theatrically while also conforming to musical requirments. A few stage plays have been taken directly as librettos, but usually a libretto is an original work or a free adaptation of a play or a novel.

Notable collaborations in operetta and musical comedy librettos include those of Sir W.S. Gilbert with Sir Arthur Sullivan of Great Britain and Lorenz Hart and Oscar Hammerstein II with Richard Rodgers of the United States.

Among composers who have successfuly written their own librettos are the German composer Richard Wagner, the French composer Hector Berlioz and the Italian American composer Gian Carlo Menotti.