The Classical era is conventionally dated from around 1750 — the death of Johann Sebastian Bach — when the dense counterpoint of the Baroque gave way to a more transparent and balanced style (the *galant*, and then Viennese Classicism). The keystone of the new language is sonata form: a movement that exposes two themes, tests them in a development, and returns home with a recapitulation. From the second half of the eighteenth century this simple plan of tension and resolution became the shared skeleton of the symphony, the string quartet, the piano sonata and the concerto. Multi-movement large forms — the four-movement symphony, the three-movement concerto — were standardised across European courts and concert rooms.

The first great architect of this language was Joseph Haydn (1732–1809). From 1761 he served for almost thirty years as music director at the Hungarian court of the Esterházy princes, writing 104 symphonies, 68 string quartets, numerous operas and oratorios for weekly performances at Eisenstadt and Esterháza. His two long London trips (1791–1795) introduced him to the public-concert economy — ticketed concerts, subscription series, printed scores for sale — and he wrote his last symphonies for that new audience. Wolfgang Amadeus Mozart (1756–1791), who broke from the service of the Salzburg archbishop in 1781 and attempted to live as a free musician in Vienna, was an early case of the 'market composer': supported by lessons, subscription concerts, music publishing and opera commissions. At his death aged thirty-five he left 41 symphonies, 27 piano concertos, and operas including *Le nozze di Figaro*, *Don Giovanni* and *Die Zauberflöte*.

The institutional change is as decisive as the works themselves. Across the eighteenth century, regular ticketed concert series emerged in London, Paris, Leipzig, Hamburg and Vienna; publishers (Artaria, Breitkopf) turned the printed score into a consumer good; the piano displaced the harpsichord and became the principal instrument of middle-class homes. The notion of a 'concert repertoire' — the idea of replaying the works of dead composers in living performance — was born in this century. By the time Ludwig van Beethoven (1770–1827) arrived in Vienna in 1792, this infrastructure was in place; he wrote much of his music with the joint support of aristocratic patrons (Lichnowsky, Lobkowitz, Razumovsky) and publishers. As his deafness advanced and he could no longer perform in public, his income depended increasingly on score publication. This institutional shift made possible the ticket economy of the 1824 premiere of the Ninth Symphony.

The end of the period is not sharp. The move from the balance and transparency of Haydn and Mozart to the larger scale and more openly personal voice of late Beethoven is, for most historians, a gradual drift rather than a clean break. The very label 'Classical' was applied retrospectively in the nineteenth century: a musicological decision to canonise three Viennese names (Haydn, Mozart, Beethoven). One cost of that canon has been the eclipse of dozens of contemporaries working in Paris, Mannheim, Stockholm or Naples — Cimarosa, Boccherini, Salieri, Cherubini, Joseph Bologne — whom current scholarship is re-opening. Still, the structural tools forged in the Classical era — sonata form, symphonic thinking, the settlement of instruments into standard chamber ensembles — have remained the basic grammar of the 'art music' tradition for the two centuries that followed.