In the late 16th century, when Renaissance polyphony was prevalent, new developments in Italy were beginning to change the sound and structure of music. Many Italian musicians disliked the polyphonic style of the Netherlanders. Wishing to emulate their image of classical Greek music, they favored less intricate compositions marked by frequent emotional contrasts, a readily understandable text, and an interplay of various voices and instruments. Such elements became especially prominent in opera, a genre first performed in Florence at the end of the 16th century and greatly developed in the 17th century by the Italian composer Claudio Monteverdi. Other new genres of vocal music included the cantata and the oratorio.
Instrumental music also became increasingly prominent during the 17th century, often in the form of a continuous contrapuntal work with no clear-cut divisions into sections or movements; it bore such names as ricercare, fantasia, and fancy. A second type of composition was made up of contrasting sections, usually in both homophonic and contrapuntal textures; this type was known as the canzona or sonata. Many instrumental pieces were based on an already existing melody or bass line; they included the theme and variations, passacaglia, chaconne, and chorale prelude. Pieces in dance rhythms were often grouped together into suites. Finally, composers developed pieces in improvisatory styles for keyboard instruments; these pieces were called preludes, toccatas, and fantasias.
With the rise of new genres in the 17th century, some of the basic concepts of musical structure were transformed, especially in Italy. Instead of writing pieces in which all voices from soprano to bass participated equally in the musical activity, composers concentrated on the soprano and bass parts and merely filled in the remaining musical space with chords. The exact spacing of the chords was unimportant, and composers often allowed a keyboard player to improvise them. The terms basso continuo, thoroughbass, and figured bass refer to the bass line and the chordal filling, which formed a texture used in all types of music, particularly in solo songs.
Another important 17th-century innovation changed the fluid style of much late Renaissance music into one marked by numerous contrasting elements; it was known variously as concertato, concertate, and concerto, from concertare (Latin, "to struggle side by side"). The contrasts occurred on many musical levels, such as contrasting instruments or contrasting densities of sound, with, for example, a single instrument opposed by a group of instruments; contrasting rates of speed; and contrasting degrees of loudness. These contrasting features were made to compete or alternate with one another in order to produce an aggressive, excited musical style, which was applied to music for all instruments as well as for the voice and was used in all forms and genres.
Outstanding composers of the 17th and early 18th centuries included the following: the Italians Arcangelo Corelli, Alessandro Scarlatti, Domenico Scarlatti, and Antonio Vivaldi; the Germans Dietrich Buxtehude and Heinrich Schütz; the Englishman Henry Purcell; the Italian-Frenchman Jean Baptiste Lully; and the Frenchman Jean Philippe Rameau.
Toward the end of the 17th century, the system of harmonic relationships called tonality began to dominate music. This development gave music an undercurrent of long-range relationships that helped to smooth out some of the abruptness of contrasts in the earlier baroque style. By the early 18th century composers had gained a firm control over the complex forces of tonality. By this time, too, they had largely abandoned the idea of frequent shifts in mood and had begun to favor a more moderate and unified approach. Often an entire piece or movement was an elaboration of one emotional quality, called an affect. The control over tonality and the emphasis on single moods were largely responsible for the feeling of security and inevitability in the music of this time, including the music of the two greatest late baroque German composers, Johann Sebastian Bach and George Frideric Handel.