Editing Sonata (section)

===Classical period===
The practice of the [[Classical music era|Classical period]] would become decisive for the sonata; the term moved from being one of many terms indicating genres or forms, to designating the fundamental form of organization for large-scale works. This evolution stretched over fifty years. The term came to apply both to the structure of individual movements (see [[Sonata form]] and [[History of sonata form]]) and to the layout of the movements in a multi-movement work. In the transition to the Classical period there were several names given to multimovement works, including [[divertimento]], [[serenade]], and [[partita]], many of which are now regarded effectively as sonatas. The usage of ''sonata'' as the standard term for such works began somewhere in the 1770s. [[Haydn]] labels his first piano sonata as such in 1771, after which the term ''divertimento'' is used sparingly in his output. The term ''sonata'' was increasingly applied to either a work for keyboard alone (see [[piano sonata]]), or for keyboard and one other instrument, often the violin or cello. It was less and less frequently applied to works with more than two instrumentalists; for example, piano trios were not often labelled ''sonata for piano, violin, and cello.''

Initially the most common layout of movements was:
# Allegro, which at the time was understood to mean not only a tempo, but also some degree of "working out", or development, of the theme.{{sfn|Rosen|1988}}{{sfn|Rosen|1997}}
# A middle movement, most frequently a [[Slow movement (music)|slow movement]]: an [[Andante (tempo)|Andante]], an [[Adagio (music)|Adagio]] or a [[Largo (music)|Largo]]; or less frequently a [[Minuet]] or [[Variation (music)|Theme and Variations]] form.
# A closing movement was generally an Allegro or a Presto, often labeled ''Finale''. The form was often a [[Rondo]] or Minuet.

However, two-movement layouts also occur, a practice Haydn uses as late as the 1790s. There was also in the early Classical period the possibility of using four movements, with a dance movement inserted before the slow movement, as in Haydn's piano sonatas No. 6 and No. 8. [[Wolfgang Amadeus Mozart|Mozart]]'s sonatas were also primarily in three movements. Of the works that Haydn labelled ''piano sonata'', ''divertimento'', or ''partita'' in [[Hoboken-Verzeichnis|Hob XIV]], seven are in two movements, thirty-five are in three, and three are in four; and there are several in three or four movements whose authenticity is listed as "doubtful." Composers such as [[Boccherini]] would publish sonatas for piano and obbligato instrument with an optional third movement—–in Boccherini's case, 28 cello sonatas.

But increasingly instrumental works were laid out in four, not three movements, a practice seen first in [[string quartet]]s and [[Symphony|symphonies]], and reaching the sonata proper in the early sonatas of [[Ludwig van Beethoven|Beethoven]]. But two- and three-movement sonatas continued to be written throughout the Classical period: Beethoven's [[Cello Sonatas Nos. 4 and 5 (Beethoven)|opus 102 pair]] has a two-movement C major sonata and a three-movement D major sonata. Nevertheless, works with fewer or more than four movements were increasingly felt to be exceptions; they were labelled as having movements "omitted," or as having "extra" movements.

The four-movement layout was by this point standard for the string quartet, and overwhelmingly the most common for the [[symphony]]. The usual order of the four movements was:

# An allegro, which by this point was in what is called [[sonata form]], complete with exposition, development, and recapitulation.
# A [[Slow movement (music)|slow movement]]: an andante, an adagio, or a largo.
# A dance movement, frequently [[minuet and trio]] or—especially later in the classical period—a [[scherzo|scherzo and trio]].
# A finale in faster tempo, often in a [[Sonata rondo form|sonata–rondo form]].

When movements appeared out of this order they would be described as "reversed", such as the scherzo coming before the slow movement in Beethoven's 9th Symphony. This usage would be noted by critics in the early 19th century, and it was codified into teaching soon thereafter.{{fact|date=March 2025}}

It is difficult to overstate the importance of Beethoven's output of sonatas: 32 piano sonatas, plus sonatas for cello and piano or violin and piano, forming a large body of music that would over time increasingly be thought essential for any serious instrumentalist to master.