Opera (English plural: operas; Italian plural: opere) is an art form in which singers and musicians perform a dramatic work combining text (called a libretto) and musical score, usually in a theatrical setting. Opera incorporates many of the elements of spoken theatre, such as acting, scenery, and costumes and sometimes includes dance. The performance is typically given in an opera house, accompanied by an orchestra or smaller musical ensemble.

Opera is part of the Western classical music tradition. It started in Italy at the end of the 16th century (with Jacopo Peri's lost Dafne, produced in Florence in 1598) and soon spread through the rest of Europe: Schütz in Germany, Lully in France, and Purcell in England all helped to establish their national traditions in the 17th century. In the 18th century, Italian opera continued to dominate most of Europe, except France, attracting foreign composers such as Handel. Opera seria was the most prestigious form of Italian opera, until Gluck reacted against its artificiality with his "reform" operas in the 1760s. Today the most renowned figure of late 18th century opera is Mozart, who began with opera seria but is most famous for his Italian comic operas, especially The Marriage of Figaro (Le Nozze Di Figaro), Don Giovanni, and Così fan tutte, as well as The Magic Flute (Die Zauberflöte), a landmark in the German tradition.