Imagine you are in a darkened theater and on stage are the actors. Behind the actors you can see the scenery. Down in front of the stage, in what is called the pit, is an orchestra and a conductor. As the orchestra plays, the actors on stage do not speak their lines they sing them!
Opera is the combination of drama and music. Like drama, opera embraces the entire spectrum of theatrical elements: dialogue, acting, costumes, scenery and action, but it is the sum of all these elements, combined with music, which defines the art form called opera.
Operatic dramas are usually serious, but there are several comic operas and funny scenes in tragic operas. The music is usually complicated and difficult to sing well.

Opera entered the 21st century as a vibrant and global art form. The first roots of modern opera first appeared in Italy in the 17th century from the Camerata (an academy of Florentine poets, musicians, and scholars). The Camerata, inspired by ancient Greek drama, sung dialogues with choruses who were accompanied by musical instruments.
Jean-Philippe Rameau, George Frederic Handel, and Christoph Willibald Gluck were the most significant opera composers of the first two-thirds of the 18th century. However, their works were surpassed by the brilliant operas of Wolfgang Amadeus Mozart. In the early 19th century, Gioacchino Rossini and Gaetano Donizetti dominated Italian opera. In the later 19th century the greatest works were those of Giuseppe Verdi and Richard Wagner. Wagner, with his bold innovations, became the most influential operatic figure since Monteverdi. Richard Strauss and Giacomo Puccini wrote the most popular late 19th- and early 20th-century operas. Though the death of Puccini in 1924 is often cited as the end of grand opera, new and often experimental works by composers such as Alban Berg, Benjamin Britten, Gian Carlo Menotti, John Adams, and Philip Glasscontinued to be produced.