These are terms used loosely, however. People are often ‘going to a symphony’ and pop songs have ‘symphony’ in their titles, but these are such casual usages that they’re almost without meaning. What, exactly, is a symphony and its function?
A symphony is an extensive composition, usually for orchestra, that consists of many parts, themes, and contrasts.
A symphony is a written piece of music, unlike a symphony orchestra, which is an orchestra equipped to play a symphony. The Boston Symphony Orchestra and London Symphony Orchestra, for instance, are arrangements of musicians large enough to perform works on a symphonic scale.
During the Middle Ages, the term sinfonia (from Greek, meaning ‘agreement’ or ‘concord’ of sound) was applied to instruments that could produce two or more sounds at once, such as the organ. As orchestras evolved across the 17th and early 18th centuries, sinfonia became used to indicate a variety of compositions.
Baroque composers such as Bach and Handel often wrote in the form of a sinfonia, which was also called an overture in their day. The most common form of sinfonia evolved from the Italian style, using three contrasting sections, or ‘movements:’ fast, slow, and fast. Normally, the sinfonia was not performed as an independent work; it occupied part of a larger composition such as an opera, oratorio, or suite.
Symphonies gradually became independent, self-contained works during the early-to-mid 18th century. Haydn and Mozart were amongst those who first wrote symphonies apart from the contexts to which they were long subordinate. The symphony later contained four movements rather than three (usually fast – slow – dance tempo – fast) and musical ideas were developed more extensively.