<P> The term, which derives from the Greek and Latin' aer' (air) first appeared in relation to music in the 14th century when it simply signified a manner or style of singing or playing . By the end of the 16th century, the term' aria' refers to an instrumental form (cf . Santino Garsi da Parma lute works,' Aria del Gran Duca'). By the early 16th century it was in common use as meaning a simple setting of strophic poetry; melodic madrigals, free of complex polyphony, were known as madrigale arioso . </P> <P> In the context of staged works and concert works, arias evolved from simple melodies into structured forms . In such works, the sung, melodic, and structured aria became differentiated from the more speech - like (parlando) recitative--broadly, the latter tended to carry the story - line, the former carried more emotional freight and became an opportunity for singers to display their vocal talent . </P> <P> The aria evolved typically in one of two forms . Binary form arias were in two sections (A--B); arias in ternary form (A--B--A) were known as da capo arias (literally' from the head', i.e. with the opening section repeated, often in a highly decorated manner). In the da capo aria the' B' episode would typically be in a different key--the dominant or relative major key . Other variants of these forms are found in the French operas of the late 17th century such as those of Jean - Baptiste Lully which dominated the period of the French baroque; vocal solos in his operas (denominated of course by the French term, airs) are frequently in extended binary form (ABB') or sometimes in rondeau form (ABACA), (a shape which is analogous to the instrumental rondo). </P> <P> In the Italian school of composers of the late 17th and early 18th century, the da capo form of aria came gradually to be associated with the ritornello (literally,' little return'), a recurring instrumental episode which was interspersed with the elements of the aria and eventually provided, in early operas, the opportunity for dancing or entries of characters . This version of aria form with ritornelli became a dominant feature of European opera throughout the 18th century . It is thought by some writers to be the origin of the instrumental forms of concerto and sonata form . The ritornelli became essential to the structure of the aria--"while the words determine the character of a melody the ritornello instruments often decided in what terms it shall be presented ." </P>

How many notes make up the accompaniment during the aria