section_path: Elements/Form
section_name: Form
paragraph_text: Form
  
  In music, form describes the overall structure or plan of a song or piece of music, and it describes the layout of a composition as divided into sections. In the early 20th century, Tin Pan Alley songs and Broadway musical songs were often in AABA thirty-two-bar form, in which the A sections repeated the same eight bar melody (with variation) and the B section provided a contrasting melody or harmony for eight bars. From the 1960s onward, Western pop and rock songs are often in verse-chorus form, which comprises a sequence of verse and chorus (" refrain ") sections, with new lyrics for most verses and repeating lyrics for the choruses. Popular music often makes use of strophic form, sometimes in conjunction with the twelve bar blues.
  
  In the tenth edition of The Oxford Companion to Music, Percy Scholes defines musical form as "a series of strategies designed to find a successful mean between the opposite extremes of unrelieved repetition and unrelieved alteration." Examples of common forms of Western music include the fugue, the invention, sonata-allegro, canon, strophic, theme and variations, and rondo.
  
  Scholes states that European classical music had only six stand-alone forms: simple binary, simple ternary, compound binary, rondo, air with variations, and fugue (although musicologist Alfred Mann emphasized that the fugue is primarily a method of composition that has sometimes taken on certain structural conventions.)
  
  Where a piece cannot readily be broken into sectional units (though it might borrow some form from a poem, story or programme), it is said to be through-composed. Such is often the case with a fantasia, prelude, rhapsody, etude (or study), symphonic poem, Bagatelle, impromptu or similar composition. Professor Charles Keil classified forms and formal detail as "sectional, developmental, or variational."