Mozart was born on January 27, 1756, at Getreidegasse 9 in Salzburg, the capital of the Archbishopric of Salzburg, an ecclesiastical principality within the Holy Roman Empire in modern-day Austria. He was the youngest of seven children born to Leopold Mozart and Anna Maria Mozart (née Pertl); five of his siblings died in infancy, leaving only Wolfgang and his elder sister, Maria Anna, born in 1751 and nicknamed Nannerl. The day after his birth, he was baptized at St. Rupert's Cathedral as Joannes Chrysostomus Wolfgangus Theophilus Mozart. In adulthood, he typically referred to himself as Wolfgang Amadè Mozart.⁹

His father, a native of Augsburg, served as a violinist and later deputy Kapellmeister in the court orchestra of the Prince-Archbishop of Salzburg. The year of Wolfgang's birth, Leopold published a widely influential textbook on violin playing, Versuch einer gründlichen Violinschule. When Nannerl began receiving keyboard lessons from her father at age seven, three-year-old Wolfgang observed closely and began picking out chords on the harpsichord.¹⁰ By the age of cuatro or five, he was playing short pieces and dictating his own miniature compositions to his father, who transcribed them.¹¹ Leopold served as his son's sole teacher in childhood, instructing him in keyboard, violin, composition, languages, and general academic subjects.

Recognizing the exceptional abilities of both children, Leopold organized a series of European concert tours to display them as prodigies before aristocratic courts and the paying public.¹² Their first journeys in 1762 took them to the Bavarian court in Munich and the imperial court in Vienna. In June 1763, the family embarked on a three-and-a-half-year grand tour across Western Europe, visiting Munich, Augsburg, Mannheim, Frankfurt, Brussels, Paris, London, The Hague, Amsterdam, and Zurich before returning to Salzburg in November 1766. During these appearances, Wolfgang astounded observers by sight-reading unfamiliar scores, improvising on themes given to him on the spot, and playing with the keyboard covered by a cloth.

In London in 1764 and 1765, the eight-year-old Mozart met Johann Christian Bach, the youngest son of Johann Sebastian Bach, who became an important mentor and compositional influence. There Wolfgang wrote his first symphonies. After a stay in Vienna from late 1767 to early 1769, where he composed the comic opera La finta semplice at age twelve, Leopold and Wolfgang made three extended journeys to Italy between December 1769 and March 1773. In Rome, Pope Clement XIV inducted the teenager into the Order of the Golden Spur. In Milan, Mozart fulfilled three major operatic commissions: Mitridate, re di Ponto (1770), Ascanio in Alba (1771), and Lucio Silla (1772).

Before departing on his first Italian tour, fourteen-year-old Mozart was appointed honorary concertmaster to the Salzburg court by Prince-Archbishop Sigismund von Schrattenbach. Following Schrattenbach's death, Hieronymus von Colloredo succeeded to the see in 1772 and promoted Mozart to salaried concertmaster. During his years in Salzburg between 1773 and 1777, Mozart had the opportunity to compose across a broad range of genres for the cathedral and the princely residence. From this period date the motet Exsultate, jubilate (K. 165), the Symphony No. 25 in G minor (K. 183) and Symphony No. 29 in A major (K. 201), a set of five violin concertos completed in 1775, six keyboard sonatas (K. 279–284), and the Piano Concerto No. 9 in E-flat major (K. 271).

Despite his productivity, Mozart grew increasingly frustrated with Salzburg. He considered his salary of 150 florins a year inadequate, resented Archbishop Colloredo's restrictions on the length of liturgical music, and lamented the city's lack of a permanent opera house. Both Wolfgang and Leopold sought a more prestigious and lucrative appointment elsewhere in Europe. When Colloredo refused Leopold permission to travel in August 1777, Wolfgang resigned his Salzburg post and set out in September 1777 on an employment-seeking tour accompanied by his mother, Anna Maria.

Their journey took them first to Munich and Augsburg, where no vacancies existed, and then to Mannheim, seat of the renowned Electoral Palatine orchestra. Mozart spent several months in Mannheim, befriending local wind and string virtuosos and falling in love with the soprano Aloysia Weber, one of four daughters of the musician Fridolin Weber. When hopes for a position at the Mannheim court failed to materialize, Leopold pressed his wife and son to continue to Paris, where they arrived in March 1778.

The Paris sojourn proved professionally disappointing and personally tragic. Although Mozart composed the Paris Symphony (No. 31 in D major, K. 297) to strong public applause for the Concert Spirituel, he turned down an organ post at Versailles and accumulated debts. On July 3, 1778, Anna Maria Mozart fell ill and died in Paris. On his slow return journey to Salzburg, Mozart learned in Munich that Aloysia Weber no longer returned his affections. Reluctantly yielding to his father's arrangements, he re-entered Archbishop Colloredo's service in January 1779 as court organist and concertmaster at an increased annual salary of 450 florins, composing the Sinfonia Concertante for Violin and Viola (K. 364) and the Coronation Mass (K. 317) before receiving a commission from Munich for the opera seria Idomeneo, which premiered with great acclaim in January 1781.

In March 1781, while Mozart was still in Munich following the premiere of Idomeneo, Archbishop Colloredo summoned him to Vienna, where the Salzburg court was attending celebrations for the accession of Emperor Joseph II. Treated by the archbishop as a domestic servant and forbidden from performing in aristocratic salons where he could earn substantial fees, Mozart quarreled bitterly with Colloredo. In May 1781, when Mozart attempted to resign, he was dismissed from service by the archbishop's steward, Count Karl Joseph Arco, literally with a kick in the seat of his trousers.

Rather than return to Salzburg, Mozart chose to settle in Vienna as a freelance musician, one of the first major composers to build a career largely free of direct ecclesiastical or aristocratic bondage.¹³ His early years in the imperial capital were marked by rapid success. On December 24, 1781, he competed in a keyboard contest before Emperor Joseph II against the Italian virtuoso Muzio Clementi, cementing his reputation as Vienna's finest pianist. His German Singspiel Die Entführung aus dem Serail (The Abduction from the Seraglio, K. 384) premiered at the Burgtheater on July 16, 1782, and was quickly staged across German-speaking Europe.

In Vienna, Mozart lodged for a time with the widowed Cäcilia Weber and her daughters, having moved from Mannheim to the capital. His affections shifted to the third daughter, the soprano Constanze Weber. Despite Leopold Mozart's strong disapproval of the match, Wolfgang and Constanze were married at St. Stephen's Cathedral on August 4, 1782. The couple had six children, of whom only two sons survived infancy: Karl Thomas Mozart (1784–1858) and Franz Xaver Wolfgang Mozart (1791–1844). During a visit by the couple to Salzburg in 1783, Constanze sang the soprano solo in the premiere of the unfinished Great Mass in C minor (K. 427).

Between 1782 and 1786, Mozart earned a substantial income through private teaching, music publication, and subscription concerts—known as academies—held in theaters, ballrooms, and aristocratic palaces. For these academies, in which he appeared as soloist and conductor, he composed a remarkable sequence of twelve piano concertos between 1784 and 1786. During this same period, he developed a close friendship with Joseph Haydn, playing chamber music with him in Vienna and dedicating to him a set of six string quartets (K. 387, 421, 428, 458, 464, and 465) published in 1785.¹⁴¹⁵ Through the library of the diplomat Baron Gottfried van Swieten, Mozart also encountered the fugal manuscripts of Johann Sebastian Bach and the oratorios of George Frideric Handel, a discovery that transformed his contrapuntal writing.¹⁶¹⁷ In December 1784, he joined the Zur Wohltätigkeit Masonic lodge; Freemasonry became a central philosophical commitment of his final seven years.¹⁸

By 1786, Mozart reduced his public appearances as a concert pianist to focus on opera, initiating his celebrated partnership with the Italian court poet Lorenzo Da Ponte.¹⁹¹ Their first collaboration, Le nozze di Figaro (The Marriage of Figaro, K. 492), adapted from Pierre Beaumarchais's politically controversial play, premiered in Vienna on May 1, 1786. Following a triumphant reception of Figaro in Prague, Mozart was commissioned to write a second Da Ponte opera for the Bohemian capital: Don Giovanni (K. 527), which premiered at the Estates Theatre in Prague on October 29, 1787. In December 1787, Emperor Joseph II appointed Mozart Imperial and Royal Chamber Composer at an annual salary of 800 florins, a part-time post that required him chiefly to compose dances for court balls. His third collaboration with Da Ponte, Così fan tutte (K. 588), followed in Vienna in January 1790.

During the late 1780s, Vienna's involvement in the Austro-Turkish War depressed the aristocratic patronage on which freelance musicians depended. Mozart's concert appearances declined, and although his household income remained substantial by general standards, his expensive lifestyle and his wife's recurring medical treatments at the spa town of Baden led him to borrow frequently from fellow Freemason Michael Puchberg. Even amidst these financial pressures, his compositional output remained extraordinary: within a matter of weeks in the summer of 1788, he completed his final three symphonies—No. 39 in E-flat major (K. 543), No. 40 in G minor (K. 550), and No. 41 in C major, the Jupiter (K. 551)—alongside the Coronation Piano Concerto (K. 537) and major string quintets and trios.

By 1791, Mozart's financial and professional prospects had improved markedly. He was secured an unpaid position as assistant and designated successor to the ailing Leopold Hofmann, the lucrative Kapellmeister of St. Stephen's Cathedral, and had received invitations for concert seasons in London and subscriptions from Hungarian and Dutch patrons. That year saw an extraordinary burst of creativity, yielding his final Piano Concerto No. 27 in B-flat major (K. 595), the String Quintet in E-flat major (K. 614), the motet Ave verum corpus (K. 618), the Clarinet Concerto in A major (K. 622) written for Anton Stadler, and two contrasting operas: the opera seria La clemenza di Tito (K. 621), commissioned for the coronation of Emperor Leopold II as King of Bohemia in Prague, and the German Singspiel Die Zauberflöte (The Magic Flute, K. 620), written with his fellow Mason Emanuel Schikaneder for a suburban Viennese theater, where it premiered to immense popular success on September 30, 1791.²⁰

In July 1791, an intermediary representing an anonymous aristocrat approached Mozart to commission a Requiem Mass in D minor (K. 626), offering half the fee in advance.²¹ The patron was Count Franz von Walsegg, an amateur musician who intended to pass the work off as his own composition in memory of his recently deceased twenty-year-old wife, Anna. Mozart worked on the Requiem intermittently during the autumn, completing the orchestration of the Introit and leaving vocal parts and figured bass drafts for the Kyrie, the Sequence up to the eighth bar of the Lacrimosa, and the Offertorium.

When Mozart began composing in the 1760s, European music was dominated by the style galant, a light, homophonic aesthetic that had emerged in reaction to the dense contrapuntal complexity of the late Baroque.²⁶ Through his extensive childhood travels, Mozart absorbed and synthesized the regional idioms of Europe: the lyrical vocal writing and opera buffa pacing of Italy, the orchestral brilliance and dynamic contrasts of the Mannheim school, French dance forms, and North German counterpoint. Over the course of his career, alongside Joseph Haydn, he forged the mature Viennese Classical style, characterized by symmetrical phrasing, clear harmonic proportions, and the dramatic tension of sonata form.

In his mature Viennese decade, particularly after his study of Bach and Handel at Baron van Swieten's Sunday recitals in 1782, Mozart reintegrated rigorous polyphony and fugal technique directly into the Classical framework. This fusion is exemplified by the finale of the String Quartet in G major (K. 387) and the culminating movement of the Jupiter Symphony (K. 551), in which five distinct musical themes are combined simultaneously in invertible counterpoint within a sonata-allegro structure.

While nineteenth-century critics often emphasized the grace, elegance, and formal symmetry of Mozart's music, twentieth- and twenty-first-century musicologists have highlighted its underlying dramatic volatility, bold chromaticism, and psychological intensity. His works in minor keys—such as the Piano Concerto No. 20 in D minor (K. 466), the Piano Concerto No. 24 in C minor (K. 491), the String Quintet in G minor (K. 516), and the Symphony No. 40 in G minor (K. 550)—employ restless rhythmic accompaniment, abrupt dynamic shifts, and dissonant harmonic progressions to convey anguish and turbulence. In his orchestration, Mozart elevated the wind section—flutes, oboes, clarinets, bassoons, and horns—from a supporting harmonic role to an independent choir capable of intricate dialogue with the strings and soloists.

Unlike almost any other major composer in Western history, Mozart wrote prolifically in every musical genre of his era and left works in each that remain cornerstones of the standard performance repertoire.²⁷

Following Mozart's death, his widow Constanze and her second husband, the Danish diplomat Georg Nikolaus von Nissen, worked to preserve his manuscripts, letters, and biography, helping to establish his posthumous reputation. Mozart's works exerted a decisive influence on the next generation of composers, above all Ludwig van Beethoven, who copied out passages of Mozart's string quartets for study, modeled several early works directly on Mozart's compositions, and wrote cadenzas for the D minor Piano Concerto (K. 466). Throughout the nineteenth and twentieth centuries, composers as stylistically diverse as Franz Schubert, Gioachino Rossini, Frédéric Chopin, Pyotr Ilyich Tchaikovsky, Gustav Mahler, and Richard Strauss revered his formal perfection.³¹ In Salzburg, the International Mozarteum Foundation, established with the support of Mozart's widow and sons in the 1840s, maintains his birthplace and family residence as museums, preserves the largest archive of family correspondence and original instruments, and hosts the annual Mozart Week festival every January.³²

Because Mozart did not assign opus numbers systematically—maintaining his own thematic catalog (Verzeichnüss aller meiner Werke) only from February 1784 until his death—his compositions are identified by numbers from the Köchel catalogue (Köchel-Verzeichnis, abbreviated K. or KV). First compiled by the Austrian botanist and musicologist Ludwig Ritter von Köchel in 1862, the chronological catalog originally listed 626 works. Subsequent scholarly revisions added newly discovered pieces, fragments, and re-dated works while removing spurious attributions. Between 1956 and 2007, international scholars produced the Neue Mozart-Ausgabe (New Mozart Edition), the authoritative critical edition of his complete works.

In September 2024, the International Mozarteum Foundation and publisher Breitkopf & Härtel released the completely revised ninth edition of the Köchel catalogue, edited by musicologist Neal Zaslaw and Ulrich Leisinger.³³ During the preparation of this edition, researchers at the Leipzig Municipal Libraries uncovered a previously unknown manuscript in the Carl Ferdinand Becker collection: a twelve-minute string trio in C major for two violins and bass consisting of seven miniature movements.³⁴ Written in dark brown ink on handmade paper around 1780, the manuscript is a copy of a lost chamber work composed by Mozart in the mid-to-late 1760s prior to his first Italian journey, likely preserved by his sister Nannerl. Entered into the new catalog as Ganz kleine Nachtmusik (KV 648), the work received its modern premiere at the Mozarteum in Salzburg on September 19, 2024, followed two days later by its German premiere at the Leipzig Opera, demonstrating the continuing scholarly discovery within Mozart's musical legacy more than two and a half centuries after his birth.