Question

What is the name of an instrumental piece at the beginning of an opera that introduces its important melodies?

Answer 1

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Overture, musical composition, usually the orchestral introduction to a musical work (often dramatic), but also an independent instrumental work. Early operas opened with a sung prologue or a short instrumental flourish, such as the trumpet “Toccata” that opens Claudio Monteverdi's Orfeo (1607).