The term concerto has been applied to music works since the early 16th century, first appearing in treatises almost a century later. Reflecting the sense of two or more forces either contending with or working together with someone (both Latin), or “arrange, agree, get together” (Italian), early concertos combined voices and instruments with no other formal consequences. These characteristics remain with the genre throughout its history. Only with the emergence of the instrumental, non-texted concerto in the late 17th century did structure begin to become an issue. Two important formal trends regarding the concerto dominate the 18th century. The most pervasive overall form is that of three movements, fast-slow-fast. The form of the first movement has attracted the most attention in the literature. Concertos in the first half of the 18th century, emanating from Italy and spreading northward, start with some version of ritornello form, which is also used in arias. In the latter part of the century, first movements increasingly take on the characteristics of sonata form, found in symphonies and sonatas, resulting in first movement concerto form or concerto-sonata form. The actual nature of the merging of the two ideas in any given work remains a vibrant topic. In one sense, the influence of the two forms, ritornello and sonata, has declined since Beethoven, giving way to other compositional concerns, yet the forms can often lurk in the background of the genre. The breadth of works that fall under the descriptive term concerto can be exasperating. Concerto also embraces a number of subgenres. The earliest works are known as vocal concertos or sacred concertos (many of them were sacred pieces), but do not always bear the designation. They are performed in stile concertato, using diverse musical forces. The term remains applicable to certain textures. The concerto grosso, connected with the Baroque, is another subgenre. Yet another subgenre is the symphonie concertante, which emerged in 18th-century France. This subgenre passed in popularity, but the term concertante continues to be applied to the texture. Later developments made use of other textures, though the symphonic concerto, originating in the 19th century, might be seen as derivative of earlier approaches. These styles and textures are major factors in many other works not called concertos, such as variation sets, fantasies, and even symphonies, to name a few.
