Opera is an art form in which singers and musicians perform a dramatic work combining text (called a libretto) and musical score. Opera is part of the Western classical music tradition. 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 started in Italy at the end of the 16th century (with Jacopo Peri's lost Dafne, produced in Florence around 1597) and soon spread through the rest of Europe: Sch√Љtz in Germany, Lully in France, and Purcell in England all helped to establish their national traditions in the 17th century. However, 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, Don Giovanni, and Cos√ђ fan tutte, as well as The Magic Flute, a landmark in the German tradition.

The first third of the 19th century saw the highpoint of the bel canto style, with Rossini, Donizetti and Bellini all creating works that are still performed today. It also saw the advent of Grand Opera typified by the works of Meyerbeer. The mid-to-late 19th century was a "golden age" of opera, led and dominated by Wagner in Germany and Verdi in Italy. The popularity of opera continued through the verismo era in Italy and contemporary French opera through to Puccini and Strauss in the early 20th century. During the 19th century, parallel operatic traditions emerged in central and eastern Europe, particularly in Russia and Bohemia. The 20th century saw many experiments with modern styles, such as atonality and serialism (Schoenberg and Berg), Neoclassicism (Stravinsky), and Minimalism (Philip Glass and John Adams). With the rise of recording technology, singers such as Enrico Caruso became known to audiences beyond the circle of opera fans. Operas were also performed on (and written for) radio and television.

Singers and the roles they play are classified by voice type, based on the tessitura, agility, power and timbre of their voices. Male singers can be loosely classified by vocal range as bass, bass-baritone, baritone, tenor and countertenor, and female singers as contralto, mezzo-soprano and soprano. (Men sometimes sing in the "female" vocal ranges, in which case they are termed sopranist or countertenor. Of these, only the countertenor is commonly encountered in opera, sometimes singing parts written for castrati вАУ men neutered at a young age specifically to give them a higher singing range.) Singers are then classified by voice type вАУ for instance, a soprano can be described as a lyric soprano, coloratura, soubrette, spinto, or dramatic soprano. These terms, although not fully describing a singing voice, associate the singer's voice with the roles most suitable to the singer's vocal characteristics. A particular singer's voice may change drastically over his or her lifetime, rarely reaching vocal maturity until the third decade, and sometimes not until middle age.