The Classical period in Western music occurred from about 1730 to 1820, despite considerable overlap at both ends with preceding and following periods, as is true for all musical eras. Although the term classical music is used as a blanket term meaning all kinds of music in this tradition, it can also occasionally mean this particular era within that tradition.

The Classical period falls between the Baroque and the Romantic periods. Probably the best known composers from this period are Wolfgang Amadeus Mozart, Joseph Haydn, and Ludwig van Beethoven, though other notable names include Muzio Clementi, Johann Ladislaus Dussek, Carl Philipp Emanuel Bach, and Christoph Willibald Gluck. Beethoven is also regarded either as a Romantic composer or a composer who was part of the transition to the Romantic; Franz Schubert is also something of a transitional figure. The period is sometimes referred to as Viennese Classic, since Mozart, Haydn, Beethoven, and Schubert all worked at some time in Vienna.

Main characteristics of music in the Classical period

• Lighter, clearer texture than Baroque music, and less complicated; mainly homophonic – melody above chordal accompaniment (but counterpoint is by no means forgotten, especially later in the period).
• An emphasis on grace and beauty of melody and form; proportion and balance, moderation and control; polished and elegant in character with expressiveness and formal structure held in perfect balance.
• More variety and contrast within a piece: of keys, melodies, rhythms and dynamics (now using crescendo and sforzando); frequent changes of mood and timbre.
• Melodies tend to be shorter than those of Baroque, with clear-cut phrases and clearly marked cadences.
• Orchestra increases in size and range; harpsichord continuo falls out of use; woodwind becomes a self-contained section.
• The harpsichord is replaced by the piano (or fortepiano): early piano music is thinnish in texture, often with Alberti bass accompaniment (Haydn and Mozart), but later becomes richer, more sonorous and powerful (Beethoven).
• Importance given to instrumental music – main kinds: sonata, trio, string quartet, symphony, concerto, serenade and divertimento.
• Sonata form develops, and becomes the most important design – used to build up the first movement of most large-scale works, but also other movements, and single pieces (such as overtures).

History of the Classical period

The Classical style as part of a larger artistic change

In the middle of the 18th century, Europe began to move to a new style in architecture, literature, and the arts generally, known as Classicism. While still tightly linked to the court culture and absolutism, with its formality and emphasis on order and hierarchy, the new style was also a cleaner style, one that favored clearer divisions between parts, brighter contrasts and colors, and simplicity rather than complexity. The remarkable development of ideas in "natural philosophy" had established itself in the public consciousness, with Newton's physics taken as a paradigm: structures should be well-founded in axioms, and articulated and orderly. This taste for structural clarity worked its way into the world of music as well, moving away from the layered polyphony of the Baroque period, and towards a style where a melody over a subordinate harmony – a combination called homophony – was preferred. This meant that playing of chords, even if they interrupted the melodic smoothness of a single part, became a much more prevalent feature of music, and this in turn made the tonal structure of works more audible. (See also counterpoint and harmony.)

The new style was also pushed forward by changes in the economic order and in social structure. As the 18th century progressed, the nobility more and more became the primary patrons of instrumental music, and there was a rise in the public taste for comic opera. This led to changes in the way music was performed, the most crucial of which was the move to standard instrumental groups, and the reduction in the importance of the "continuo", the harmonic fill beneath the music, often played by several instruments. One way to trace this decline of the continuo and its figured chords is to examine the decline of the term "obbligato", meaning a mandatory instrumental part in a work of chamber music. In the Baroque world, additional instruments could be optionally added to the continuo; in the Classical world, all parts were noted specifically, though not always notated, as a matter of course, so the word "obbligato" became redundant. By 1800, the term was virtually extinct, as was the practice of conducting a work from the keyboard.

The changes in economic situation just noted also had the effect of altering the balance of availability and quality of musicians. While in the late Baroque a major composer would have the entire musical resources of a town to draw on, the forces available at a hunting lodge were smaller, and more fixed in their level of ability. This was a spur to having primarily simple parts to play, and in the case of a resident virtuoso group, a spur to writing spectacular, idiomatic parts for certain instruments, as in the case of the Mannheim orchestra. In addition, the appetite for a continual supply of new music, carried over from the Baroque, meant that works had to be performable with, at best, one rehearsal. Indeed, even after 1790 Mozart writes about "the rehearsal", to imply that his concerts would have only one.

Since polyphonic texture was no longer the focus of music, but rather a single melodic line with accompaniment, there was greater emphasis on notating that line for dynamics and phrasing. The simplification of texture made such instrumental detail more important, and also made the use of characteristic rhythms, such as attention-getting opening fanfares, the funeral march rhythm, or the minuet genre, more important in establishing and unifying the tone of a single movement.

This led to the Classical style's gradual breaking with the Baroque habit of making each movement of music devoted to a single "affect" or emotion. Instead, it became the style to establish contrasts between sections within movements, giving each its own emotional coloring, using a range of techniques: opposition of major and minor; strident rhythmic themes in opposition to longer, more song-like themes; and especially, making movement between different harmonic areas the principal means of creating dramatic contrast and unity. Transitional episodes became more and more important, as occasions of surprise and delight. Consequently composers and musicians began to pay more attention to these, highlighting their arrival, and making the signs that pointed to them, on one hand, more audible, and on the other hand, more the subject of "play" and subversion – that is, composers more and more created false expectations, only to have the music skitter off in a different direction.

Beginnings of the Classical style (1730-1760)

At first the new style took over Baroque forms – the ternary "da capo aria" and the "sinfonia" and "concerto" – and composed with simpler parts, more notated ornamentation and more emphatic division into sections. However, over time, the new aesthetic caused radical changes in how pieces were put together, and the basic layouts changed. (See History of sonata form.) Composers from this period sought dramatic effects, striking melodies, and clearer textures. The Italian composer Domenico Scarlatti was an important figure in the transition from Baroque to Classical. His unique composition style is strongly related to that of the early Classical period. He is best known for composing more than five hundred one-movement keyboard sonatas. Another important break with the past was the radical overhaul of opera by Christoph Willibald Gluck, who cut away a great deal of the layering and improvisational ornament, and focused on the points of modulation and transition. By making these moments where the harmony changes more focal, he enabled powerful dramatic shifts in the emotional color of the music. To highlight these episodes he used changes in instrumentation, melody, and mode. Among the most successful composers of his time, Gluck spawned many emulators, one of whom was Antonio Salieri. Their emphasis on accessibility was hugely successful in opera, and in vocal music more widely: songs, oratorios, and choruses. These were considered the most important kinds of music for performance, and hence enjoyed greatest success in the public estimation.

The phase between the Baroque and the rise of the Classical, with its broad mixture of competing ideas and attempts to unify the different demands of taste, economics and "worldview", goes by many names. It is sometimes called "Galant", "Rococo", or "pre-Classical", or at other times, "early Classical". It is a period where composers still working in the Baroque style are still successful, if sometimes thought of as being more of the past than the present – Bach, Handel and Telemann all compose well beyond the point at which the homophonic style is clearly in the ascendant. Musical culture was caught at a crossroads: the masters of the older style had the technique, but the public hungered for the new. This is one of the reasons C.P.E. Bach was held in such high regard: he understood the older forms quite well, and knew how to present them in new garb, with an enhanced variety of form; he went far in overhauling the older forms from the Baroque.

The early Classical style (1760-1775)

By the late 1750s there are flourishing centers of the new style in Italy, Vienna, Mannheim, and Paris; dozens of symphonies are composed, and there are "bands" of players associated with theatres. Opera or other vocal music is the feature of most musical events, with concerti and "symphonies", which would over the course of the Classical develop and become independent instrumental works (see symphony), serving as instrumental interludes and introductions, for operas, and for even church services. The norms of a body of strings supplemented by winds, and of movements of particular rhythmic character, are established by the late 1750s in Vienna. But the length and weight of pieces is still set with some Baroque characteristics: individual movements still focus on one affect or have only one sharply contrasting middle section, and their length is not significantly greater than Baroque movements. It should also be noted that at this time there is not yet a clearly enunciated theory of how to compose in the new style. It was a moment ripe for a breakthrough.

Many consider this breakthrough to have been made by C.P.E. Bach, Gluck, and several others. Indeed, C.P.E. Bach and Gluck are often considered to be founders of the Classical style itself.

The first great master of the style was the composer Joseph Haydn. In the late 1750s he began composing symphonies, and by 1761 he had composed a triptych ("Morning", "Noon", and "Evening") solidly in the "contemporary" mode. As a "vice-Kapellmeister" and later "Kapellmeister", his output expanded: he would compose over forty symphonies in the 1760s alone. And while his fame grew, as his orchestra was expanded and his compositions were copied and disseminated, his voice was only one among many.

While some suggest that he was overshadowed by Mozart and Beethoven, it would be difficult to overstate Haydn's centrality to the new style, and therefore to the future of Western art music as a whole. At the time, before the pre-eminence of Mozart or Beethoven, and with Johann Sebastian Bach known primarily to connoisseurs of keyboard music, Haydn reached a place in music that set him above all other composers except perhaps George Friedrich Handel. Some have pointed out that he occupieda place equivalent to the Beatles, for example, in the history of Rock and Roll. It was he who, more than any other single individual, realized that the evolving new style needed to be directed by new ideas and principles. He took existing ideas, and radically altered how they functioned – earning him the titles "father of the symphony," and "father of the string quartet." One might truly say that he was the father of the sonata form – which, in its Classical flowering, relied on dramatic contrast, tension of melody against harmony and rhythm, and required the audience to follow a dramatic curve over a larger span of time than was previously necessary.

Strangely enough, one of the forces that worked as an impetus for his pressing forward was the first stirring of what would later be called "Romanticism" – the "Sturm und Drang", or "storm and stress" phase in the arts, a short period where obvious emotionalism was a stylistic preference: the fad of the 1770s. Haydn accordingly wanted more dramatic contrast and more emotionally appealing melodies, with sharpened character and individuality. This period faded away in music and literature: however, it would color what came afterward, and eventually be a component of aesthetic taste in coming decades.

The "Farewell" Symphony, No. 45 in F# Minor, exemplifies Haydn's integration of the differing demands of the new style, with surprising sharp turns, and a long adagio to end the work. In 1772, Haydn completed his Opus 20 set of six string quartets, in which he deploys the polyphonic techniques he gathered from the previous era to provide structural coherence capable of holding together his melodic ideas. For some this marks the beginning of the "mature" Classical style, where the period of reaction against the complexity of the late Baroque begins to be replaced with a period of integration of elements of both Baroque and Classical styles.

The middle Classical style (1775-1790)

Haydn, having worked for over a decade as the music director for a prince, had far more resources and scope for composing than most, and also the ability to shape the forces that would play his music. This opportunity was not wasted, as Haydn, beginning quite early on his career, restlessly sought to press forward the technique of building ideas in music (see development). His next important breakthrough was in the Opus 33 string quartets (1781), where the melodic and the harmonic roles segue among the instruments: it is often momentarily unclear what is melody and what is harmony. This changes the way the ensemble works its way between dramatic moments of transition and climactic sections: the music flows smoothly and without obvious interruption. He then took this integrated style and began applying it to orchestral and vocal music.

Haydn's gift to music was a way of composing, a way of structuring works, which was at the same time in accord with the governing aesthetic of the new style. It would, however, be a younger contemporary, Wolfgang Amadeus Mozart, who would bring his genius to Haydn's ideas, and apply them to two of the major genres of the day: opera, and the virtuoso concerto. Whereas Haydn spent much of his working life as a court composer, Mozart wanted public success in the concert life of cities. This meant opera, and it meant performing as a virtuoso. Haydn was not a virtuoso at the international touring level; nor was he seeking to create operatic works that could play for many nights in front of a large audience. Mozart wanted both. Moreover, Mozart also had a taste for more chromatic chords (and greater contrasts in harmonic language generally), a greater love for creating a welter of melodies in a single work, and a more Italianate sensibility in music as a whole. He found, in Haydn's music, and later in his study of the polyphony of Bach, the means to discipline and enrich his gifts.

Mozart rapidly came to the attention of Haydn, who hailed the new composer, studied his works, and considered the younger man his only true peer in music. Their letters to each other are filled with the kind of asides that only two people working at a higher plane than their contemporaries can share. In Mozart, Haydn found a greater range of instrumentation, dramatic effect and melodic resource – the learning relationship moved in two directions.

Mozart's arrival in Vienna in 1780 brought an acceleration in the development of the Classical style. There Mozart absorbed the fusion of Italianate brilliance and Germanic cohesiveness which had been brewing for the previous 20 years. His own taste for brilliances, rhythmically complex melodies and figures, long cantilena melodies, and virtuoso flourishes was merged with an appreciation for formal coherence and internal connectedness. Strangely enough, it is at this point that war and inflation halted a trend to larger and larger orchestras and forced the disbanding or reduction of many theatre orchestras. This pressed the Classical style inwards: towards seeking greater ensemble and technical challenge – for example, scattering the melody across woodwinds, or using thirds to highlight the melody taken by them. This process placed a premium on chamber music for more public performance, giving a further boost to the string quartet and other small ensemble groupings.

It was during this decade that public taste began, increasingly, to recognize that Haydn and Mozart had reached a higher standard of composition. By the time Mozart arrived at age 25, in 1781, the dominant styles of Vienna were recognizably connected to the emergence in the 1750s of the early Classical style. By the end of the 1780s, changes in performance practice, the relative standing of instrumental and vocal music, technical demands on musicians, and stylistic unity had become established in the composers who imitated Mozart and Haydn. During this decade Mozart would compose his most famous operas, his six late symphonies which would help redefine the genre, and a string of piano concerti which still stand at the pinnacle of these forms.

One composer who was influential in spreading the more serious style that Mozart and Haydn had formed is Muzio Clementi, a gifted virtuoso pianist who dueled Mozart to a draw before the Emperor, when they exhibited their compositions in performance. His own sonatas for the piano circulated widely, and he became the most successful composer in London during the 1780s. The stage was set for a generation of composers who, having absorbed the lessons of the new style earlier, and having clear examples to aim at, would take the Classical style in new directions. Also in London at this time was Johann Ladislaus Dussek, who, like Clementi, encouraged piano makers to extend the range and other features of their instruments, and then fully exploited the newly opened possibilities. The importance of London in the Classical period is often overlooked – but it served as the home to the Broadwood's factory for piano manufacturing, and as the base for composers who, while less famous than the "Vienna School", would have a decisive influence on what came later. They were composers of a number of fine works, notable in their own right. London's taste for virtuosity may well have encouraged the complex passage work and extended statements on tonic and dominant.

The late Classical style (1790-1825)

When Haydn and Mozart began composing, symphonies were played as single movements before, between, or as interludes within other works, and many of them lasted only ten or twelve minutes; instrumental groups had varying standards of playing and the "continuo" was a central part of music-making. In the intervening years, the social world of music had seen dramatic changes: international publication and touring had grown explosively, concert societies were beginning to be formed, notation had been made more specific, more descriptive, and schematics for works had been simplified (yet became more varied in their exact working out). In 1790, just before Mozart's death, with his reputation spreading rapidly, Haydn was poised for a series of successes, notably his late oratorios and "London" symphonies. Composers in Paris, Rome and all over Germany turned to Haydn and Mozart for their ideas on form.

The moment was again ripe for a dramatic shift. The decade of the 1790s saw the emergence of a new generation of composers, born around 1770, who, while they had grown up with the earlier styles, found in the recent works of Haydn and Mozart a vehicle for greater expression. In 1788 Luigi Cherubini settled in Paris, and in 1791 composed "Lodoiska", an opera that shot him to fame. Its style is clearly reflective of the mature Haydn and Mozart, and its instrumentation gave it a weight that had not yet been felt in the grand opera. His contemporary Étienne Méhul extended instrumental effects with his 1790 opera "Euphrosine et Coradin", from which followed a series of successes.

Of course, the most fateful of the new generation would be Ludwig van Beethoven, who launched his numbered works in 1794 with a set of three piano trios, which remain in the repertoire. Somewhat younger than these, though equally accomplished because of his youthful study under Mozart and his native virtuosity, was Johann Nepomuk Hummel. Hummel studied under Haydn as well; he was a friend to Beethoven and Schubert, and a teacher to Franz Liszt. He concentrated more on the piano than any other instrument, and his time in London in 1791 and 1792 saw the composition, and publication in 1793, of three piano sonatas, opus 2, which idiomatically used Mozart's techniques of avoiding the expected cadence, and Clementi's sometimes modally uncertain virtuoso figuration. Taken together, these composers can be seen now as the vanguard of a broad change in style and the center of gravity in music. They would study one another's works, copy one another's gestures in music, and on occasion behave like quarrelsome rivals.

The crucial differences with the previous wave can be seen in the downward shift in melodies, increasing durations of movements, the acceptance of Mozart and Haydn as paradigmatic, the greater and greater use of keyboard resources, the shift from "vocal" writing to "pianistic" writing, the growing pull of the minor and of modal ambiguity, and the increasing importance of varying accompanying figures to bring "texture" forward as an element in music. In short, the late Classical was seeking a music that was internally more complex. The growth of concert societies and amateur orchestras, marking the importance of music as part of middle-class life, contributed to a booming market for pianos, piano music, and virtuosi to serve as examplars. Hummel, Beethoven, Clementi were all renowned for their improvising.

One explanation for the shift in style has been advanced by Schoenberg and others: the increasing centrality of the idea of theme and variations in compositional thinking. Schoenberg argues that the Classical style was one of "continuing variation", where a development was, in effect, a theme and variations with greater continuity. In any event, theme and variations replaced the fugue as the standard vehicle for improvising, and was often included, directly or indirectly, as a movement in longer instrumental works.

Direct influence of the Baroque continued to fade: the figured bass grew less prominent as a means of holding performance together, the performance practices of the mid 18th century continued to die out. However, at the same time, complete editions of Baroque masters began to become available, and the influence of Baroque style, as the Classical period understood it, continued to grow, particularly in the ever more expansive use of brass. Another feature of the period is the growing number of performances where the composer was not present. This led to increased detail and specificity in notation; for example, there were fewer and fewer "optional" parts that stood separately from the main score.

The force of these shifts would be abundantly apparent with Beethoven's 3rd Symphony, given the name "Eroica", which is Italian for "heroic", by the composer. As with Stravinsky's Rite of Spring, it may not have been the first in all of its innovations, but its aggressive use of every part of the Classical style set it apart from its contemporary works: in length, ambition, and harmonic resources.

Classical influence on later composers

Musical eras seldom disappear at once; instead, features are replaced over time, until the old is simply felt as "old-fashioned". The Classical style did not "die" so much as transform under the weight of changes.

One crucial change was the shift towards harmonies centering around "flatward" or subdominant keys. In the Classical style, major key was far more common than minor, chromaticism being moderated through the use of "sharpward" modulation, and sections in the minor mode were often merely for contrast. Beginning with Mozart and Clementi, there began a creeping colonization of the subdominant region. With Schubert, subdominant moves flourished after being introduced in contexts in which earlier composers would have confined themselves to dominant shifts (For a fuller discussion of these terms see Tonality.). This introduced darker colors to music, strengthened the minor mode, and made structure harder to maintain. Beethoven would contribute to this, by his increasing use of the fourth as a consonance, and modal ambiguity – for example, the opening of the D Minor Symphony.

Among this generation of "Classical Romantics" Franz Schubert, Carl Maria von Weber, and John Field are among the most prominent, along with the young Felix Mendelssohn. Their sense of form was strongly influenced by the Classical style, and they were not yet "learned" (imitating rules which were codified by others), but directly responding to works by Beethoven, Mozart, Clementi, and others, as they encountered them. The instrumental forces at their disposal were also quite "Classical" in number and variety, permitting similarity with avowedly Classical works.

However, the forces destined to end the hold of the Classical style gather strength in the works of each of these composers. The most commonly cited one is, of course, harmonic innovation. However, also important is the increasing focus on having a continuous and rhythmically uniform accompanying figuration. Beethoven's Moonlight Sonata would be the model for hundreds of later pieces – where the shifting movement of a rhythmic figure provides much of the drama and interest of the work, while a melody drifts above it. As years wore on, greater knowledge of works, greater instrumental expertise, increasing variety of instruments, the growth of concert societies, and the unstoppable domination of the piano – which created a huge audience for sophisticated music – all contributed to the shift to the "Romantic" style.

Drawing the line exactly is impossible: there are sections of Mozart's works which, taken alone, are indistinguishable in harmony and orchestration from music written 80 years later, and composers continue to write in normative Classical styles all the way into the 20th century. Even before Beethoven's death, composers such as Louis Spohr were self-described Romantics, incorporating, for example, more and more extravagant chromaticism in their works. However, generally the fall of Vienna as the most important musical center for orchestral composition is felt to be the occasion of the Classical style's final eclipse, along with its continuous organic development of one composer learning in close proximity to others. Franz Liszt and Frédéric Chopin visited Vienna when young, but they then moved on to other vistas. Composers such as Carl Czerny, while deeply influenced by Beethoven, also searched for new ideas and new forms to contain the larger world of musical expression and performance in which they lived.

Renewed interest in the formal balance and restraint of 18th century classical music led in the early 20th century to the development of so-called Neoclassical style, which numbered Stravinsky and Prokofiev among its proponents.