An overture is an orchestral piece that serves as an introduction to an opera. It typically features themes and motifs from the opera's main musical numbers, setting the mood and preparing the audience for the story to unfold. Overtures can vary in length and complexity, often showcasing the orchestra's capabilities. In the context of opera, the overture is performed before the curtain rises, allowing the audience to immerse themselves in the musical world of the production. Famous examples include the overtures from Giuseppe Verdi's "La Traviata" and Richard Wagner's "The Flying Dutchman."