Beethoven was born in Bonn and raised in rather unhappy surroundings. His early signs of musical talent were subjected to the whimsical discipline of his father, a singer in the court chapel. Because of his father's alcoholism, the young Beethoven became a court musician in 1789, in order to support his family. His early compositions under the tutelage of German composer Christian Gottlob Neefe revealed a considerable talent, and it was planned that Beethoven study in Vienna, Austria, with Wolfgang Amadeus Mozart. Although Mozart's death in 1791 prevented this, Beethoven moved to Vienna in 1792 and became a pupil of Austrian composer Joseph Haydn.

In Vienna, Beethoven impressed the aristocracy with his piano improvisations. In composition he steered a middle course between the stylistic extravagance of German composer Carl Philipp Emanuel Bach and the refinement of Mozart. Meanwhile, he entered into increasingly favourable arrangements with Austrian music publishers. The expanding market for published music enabled Beethoven to make a living as a freelance composer, a path that Mozart, a decade earlier, had found full of frustration.

Beethoven tended to choose unattainable women—aristocratic or married or both. In a letter to an "Immortal Beloved" ( now dated at 1812), he expressed his conflicting feelings for the woman who may have been the sole person ever to reciprocate his declarations. Her identity was solved beyond reasonable doubt in 1977 by American musicologist Maynard Solomon, who identified her as Antonie Brentano, the wife of a Frankfurt merchant and a mother of four. Conceivably, Beethoven's sense of virtue and fear of marriage contributed to his flight from this relationship.

By 1818 Beethoven had become virtually deaf and relied on small "conversation books" in which visitors wrote their remarks to him. He withdrew from all but a steadily shrinking circle of friends. Except for the premieres of his Symphony no. 9 and parts of the Missa solemnis in 1824, his music remained fashionable only among a small group of connoisseurs. His prestige was still such, however, that during his last illness he received huge outpourings of sympathy. He died in Vienna on March 26, 1827. Tens of thousands witnessed his funeral procession.

In the first decade of the 19th century Beethoven abandoned the sectional, loosely constructed style of works such as the popular Septet op. 20, for strings and winds, and turned to a fresh expansion of the musical language bequeathed by Haydn and Mozart. Beethoven soon revealed his complete assimilation of the Viennese classical style in every major instrumental genre: symphony, concerto, string quartet, and sonata. The majority of the works for which he is most readily remembered today were composed during the decade bounded by the Symphony no. 3 (Eroica, begun 1803; first performed, 1805) and the Symphony no. 8 (1812), a period known as his heroic decade.

Beethoven's major output consists of 9 symphonies, 7 concertos (5 for piano), 17 string quartets, 32 piano sonatas, 10 sonatas for violin and piano, 5 sonatas for cello and piano, an opera, 2 masses (see Mass, Musical Settings of), several overtures (see Overture), and numerous sets of piano variations. He has traditionally been referred to as music's "bridge to romanticism," and his oeuvre is simplistically divided into three roughly equal periods. Today most scholars view him as the last great representative of the Viennese classical style, a composer who at two important junctures in his life turned away from the aesthetic of the emerging romantic period in favor of renewed exploration of the legacy of Haydn and Mozart. After arriving in Vienna, Beethoven alternated between compositions based openly on classical models, such as the String Quartet in A Major op. 18 no. 5 (1800; patterned on Mozart's String Quartet K. 464), and those based on looser Italianate structures, such as the song "Adelaide" (1795).

The "new manner" that Beethoven announced for his work in a conversation with a friend in 1802 marks his first return to the Viennese classical tradition. Although his works of the decade from 1802 to 1812 project a heroic aura, musically they represent an expansion of the tighter forms of Haydn and Mozart. This is apparent both in works of unprecedented scope, such as the Eroica Symphony and the Piano Concerto no. 5 (Emperor, 1809), and in formally compressed works such as the Symphony no. 5 (1808) and the Piano Sonata op. 57 (Appassionata, 1805). In these works Beethoven proved that a style founded on thematic integration and on the harmonic polarization achieved by manipulating opposing keys could produce works of remarkable expressive power.

The completion of the Symphony no. 8 and the fading of hopes for a successful relationship with the "Immortal Beloved" left Beethoven in a state of compositional uncertainty. His prodigious output of the previous decade ceased. The few works of the years after 1812—such as the op. 98 song cycle An die ferne Geliebte (To the Distant Beloved, 1816) and the Piano Sonata in A Major op. 101 (1817)—took on an experimental hue, reviving and expanding on the more relaxed musical structures Beethoven had employed in the 1790s. The handful of open-ended, cyclic works of this period exercised the most direct musical influence on the succeeding generation of romantic composers (apparent, for example, in the song cycles of German composer Robert Schumann). In 1818 Beethoven inaugurated a second return to the tightly structured heroic style. The move was marked by the Piano Sonata in B-flat Major op. 106 (Hammerklavier), a work of unprecedented length and difficulty.

The works of Beethoven's last period, rather than having been composed in sets or even in pairs, are each marked by an individuality that later composers would admire but could scarcely emulate. In the Ninth Symphony and the Missa solemnis Beethoven gave expression to an all-embracing view of idealized humanity largely rooted in the Enlightenment and more compelling than the equally lofty ideals portrayed a decade earlier in his only opera, Fidelio (1814). The dominant private dimension of Beethoven's late style gave rise to the five string quartets of 1824 to 1826, the last two of which were written without commissions. In these works Beethoven achieved an ideal synthesis between popular and learned styles and between the humorous and the sublime. Judged inaccessible in their time, the string quartets have become—as has so much of Beethoven's output—yardsticks against which all other musical achievements are measured.

Beethoven towered over the 19th century, embodying the heroic ideal and the romantic perception of the composer as an artist who pursues a personal vision beyond the creation of music by order of an ecclesiastical or aristocratic patron. However, Beethoven's immediate musical influence was limited. For some composers—such as Johannes Brahms, who produced no symphony until his 40s—Beethoven's legacy was paralyzing. Although German composer Richard Wagner invoked Beethoven's Ninth Symphony, particularly its choral finale, as support for his own vision of the music drama, it was not until the late romantic symphonies of Austrian composers Anton Bruckner and, especially, Gustav Mahler that Beethoven's symphonic ideal was carried to what is often regarded as its final stage of development. Today Beethoven's works form the core of orchestral and chamber music repertoires worldwide.