An overture is a musical introduction that typically precedes an opera, ballet, or orchestral concert. It serves to set the mood and introduce themes that will be explored in the main work. Overtures can be purely instrumental or may include vocal elements, depending on the context. Historically, overtures were often used to signal the beginning of a performance and to capture the audience's attention. Famous examples include the William Tell Overture by Gioachino Rossini and the Overture to The Marriage of Figaro by Wolfgang Amadeus Mozart. These pieces are celebrated for their melodic and thematic richness.