Classical music refers to the art music of the Western world, distinct from folk or popular traditions, and is characterized by its formality, complex musical forms, and sophisticated written notation since at least the 9th century. Rooted in medieval churches and royal courts, early developments included the unification of plainchant into Gregorian chant and the polyphonic innovations of the 12th-century Notre-Dame school in France, alongside secular troubadour traditions.

The Baroque period (1580–1750) saw the standardization of common-practice tonality and the birth of opera, concertos, and fugues, famously championed by Johann Sebastian Bach. The pivotal Classical period (1730–1820) featured masters like Wolfgang Amadeus Mozart, Joseph Haydn, and Ludwig van Beethoven, who created iconic symphonies, string quartets, and concertos. Subsequently, Romantic music (1800–1910) embraced programmatic themes, celebrated virtuosity, and incorporated nationalism, as seen in the operas of Richard Wagner.

By the 20th century, stylistic unity dissipated as composers explored modernism, some abandoning tonality for serialism, while others drew inspiration from folk melodies or Impressionism, all amid the increasing prominence of popular music.