• Composer Nicola (Antonio) Porpora, 1686
• Composer Wolfgang Amadeus Mozart, 1756

Porpora was born in Naples. He graduated from the music conservatory Poveri di Gesù Cristo of his native city, where the civic opera scene was dominated by Alessandro Scarlatti.

Porpora's first opera, Agrippina, was successfully performed at the Neapolitan court in 1708. His second, Berenice, was performed at Rome. In a long career, he followed these up by many further operas, supported as maestro di cappella in the households of aristocratic patrons, such as the commander of military forces at Naples, prince Philip of Hesse - Darmstadt, or of the Portuguese ambassador at Rome, for composing operas alone did not yet make a viable career. However, his enduring fame rests chiefly upon his unequaled power of teaching singing. At the Neapolitan Conservatorio di Sant' Onofrio and with the Poveri di Gesù Cristo he trained Farinelli, Caffarelli, Salimbeni, and other celebrated vocalists, during the period 1715 - 1721. In 1720 and 1721 he wrote two serenades to librettos by a gifted young poet, Metastasio, the beginning of a long, though interrupted, collaboration. In 1722 his operatic successes encouraged him to lay down his conservatory commitments.

After a rebuff from the court of Charles VI at Vienna in 1725, Porpora settled mostly in Venice, composing and teaching regularly in the schools of La Pietà and the Incurabili. In 1729 the anti - Handel clique invited him to London to set up an opera company as a rival to Handel's, without success, and in the 1733 - 1734 season, even the presence of his pupil, the great Farinelli, failed to save the dramatic company in Lincoln's Inn Fields (the "Opera of the Nobility") from bankruptcy.

An interval as Kapellmeister at the Dresden court of the Elector of Saxony from 1748 ended in strained relations with his rival in Venice and Rome, the hugely successful opera composer Johann Adolph Hasse and his wife, the prima donna Faustina, and resulted in Porpora's departure in 1752. From Dresden he went to Vienna, where he gave music lessons to the young Joseph Haydn, who lived with Porpora as accompanist and in the character of a valet, but allowed later that he had learned from the maestro "the true fundamentals of composition". Then Porpora returned in 1759 to Naples.

From this time Porpora's career was a series of misfortunes: his florid style was becoming old fashioned, his last opera, Camilla, failed, his pension from Dresden stopped, and he became so poor that the expenses of his funeral were paid by a subscription concert. Yet at the moment of his death Farinelli and Caffarelli were living in splendid retirement on fortunes largely based on the excellence of the old maestro's teaching.

A good linguist, who was admired for the idiomatic fluency of his recitatives, and a man of considerable literary culture, Porpora was also celebrated for his conversational wit. He was well read in Latin and Italian literature, wrote poetry and spoke French, German and English.

Besides some four dozen operas, there are oratorios, solo cantatas with keyboard accompaniment, motets and vocal serenades. Among his larger works, his 1720 opera Orlando, one mass, his Venetian Vespers, and the opera Arianna in Nasso (1733) have been recorded .

Mozart showed prodigious ability from his earliest childhood in Salzburg. Already competent on keyboard and violin, he composed from the age of five and performed before European royalty. At 17, he was engaged as a court musician in Salzburg, but grew restless and traveled in search of a better position, always composing abundantly. While visiting Vienna in 1781, he was dismissed from his Salzburg position. He chose to stay in the capital, where he achieved fame but little financial security. During his final years in Vienna, he composed many of his best known symphonies, concertos, and operas, and portions of the Requiem, which was largely unfinished at the time of his death. The circumstances of his early death have been much mythologized. He was survived by his wife Constanze and two sons.

Mozart learned voraciously from others, and developed a brilliance and maturity of style that encompassed the light and graceful along with the dark and passionate. His influence on subsequent Western art music is profound. Beethoven wrote his own early compositions in the shadow of Mozart, and Joseph Haydn wrote that "posterity will not see such a talent again in 100 years."

Wolfgang Amadeus Mozart was born to Leopold and Anna Maria Pertl Mozart at 9 Getreidegasse in Salzburg, capital of the sovereign Archbishopric of Salzburg in what is now Austria, but then was part of the Holy Roman Empire. His only sibling to survive infancy was his elder sister Maria Anna (1751 – 1829), nicknamed "Nannerl". Mozart was baptized the day after his birth at St. Rupert's Cathedral. The baptismal record gives his name in Latinized form as Joannes Chrysostomus Wolfgangus Theophilus Mozart. He generally called himself "Wolfgang Amadè Mozart" as an adult, but there were many variants.

His father (1719 – 1787) was from Augsburg. A minor composer and an experienced teacher, he was deputy Kapellmeister to the court orchestra of the Archbishop of Salzburg. In the year of Mozart's birth, his father published a violin textbook, Versuch einer gründlichen Violinschule, which achieved success.

When Nannerl was seven, she began keyboard lessons with her father while her three year old brother looked on. Years later, after her brother's death, she reminisced:

He often spent much time at the clavier, picking out thirds, which he was ever striking, and his pleasure showed that it sounded good. [...] In the fourth year of his age his father, for a game as it were, began to teach him a few minuets and pieces at the clavier. [...] He could play it faultlessly and with the greatest delicacy, and keeping exactly in time. [...] At the age of five, he was already composing little pieces, which he played to his father who wrote them down.

These early pieces, K. 1–5, were recorded in the Nannerl Notenbuch.

Biographer Maynard Solomon notes that, while Mozart's father was a devoted teacher to his children, there is evidence that Mozart was keen to progress beyond what he was taught. His first ink spattered composition and his precocious efforts with the violin were of his own initiative and came as a surprise to his father. Mozart's father eventually gave up composing when his son's musical talents became evident. In his early years, Mozart's father was his only teacher. Along with music, he also taught his children languages and academic subjects.

During Mozart's youth, his family made several European journeys in which he and Nannerl performed as child prodigies. These began with an exhibition, in 1762, at the court of the Prince elector Maximilian III of Bavaria in Munich, and at the Imperial Court in Vienna and Prague. A long concert tour spanning three and a half years followed, taking the family to the courts of Munich, Mannheim, Paris, London, The Hague, again to Paris, and back home via Zurich, Donaueschingen, and Munich.

During this trip, Mozart met a great number of musicians and acquainted himself with the works of other composers. A particularly important influence was Johann Christian Bach, whom Mozart visited in London in 1764 and 1765. The family again went to Vienna in late 1767 and remained there until December 1768. In 1767, during this period, Mozart composed the Latin drama Apollo et Hyacinthus first performed in Salzburg University.

These trips were often difficult and travel conditions were primitive. The family had to wait for invitations and reimbursement from the nobility and they endured long, near fatal illnesses far from home: first Leopold (London, summer 1764) then both children (The Hague, autumn 1765).

After one year in Salzburg, father and son set off for Italy, leaving Mozart's mother and sister at home. This travel lasted from December 1769 to March 1771. As with earlier journeys, Mozart's father wanted to display his son's abilities as a performer and a rapidly maturing composer. Mozart met G.B. Martini, in Bologna, and was accepted as a member of the famous Accademia Filarmonica. In Rome, he heard Gregorio Allegri's Miserere once in performance in the Sistine Chapel and wrote it out from memory, thus producing the first illegal copy of this closely guarded property of the Vatican.

In Milan, Mozart wrote the opera Mitridate, re di Ponto (1770), which was performed with success. This led to further opera commissions. He returned with his father later twice to Milan (August – December 1771; October 1772 – March 1773) for the composition and premieres of Ascanio in Alba (1771) and Lucio Silla (1772). Mozart's father hoped these visits would result in a professional appointment for his son in Italy, but these hopes were never realized.

Toward the end of the final Italian journey, Mozart wrote the first of his works to be still widely performed today, the solo motet Exsultate, jubilate, K. 165.

After finally returning with his father from Italy on 13 March 1773, Mozart was employed as a court musician by the ruler of Salzburg, Prince - Archbishop Hieronymus Colloredo. The composer had a great number of friends and admirers in Salzburg and had the opportunity to work in many genres, composing symphonies, sonatas, string quartets, serenades, and a few minor operas. Between April and December 1775, Mozart developed an enthusiasm for violin concertos, producing a series of five (the only ones he ever wrote), which steadily increased in their musical sophistication. The last three - K. 216, K. 218, K. 219 - are now staples of the repertoire. In 1776 he turned his efforts to piano concertos, culminating in the E-flat concerto K. 271 of early 1777, considered by critics to be a breakthrough work.

Despite these artistic successes, Mozart grew increasingly discontented with Salzburg and redoubled his efforts to find a position elsewhere. One reason was his low salary, 150 florins a year; Mozart also longed to compose operas, and Salzburg provided only rare occasions for these. The situation worsened in 1775 when the court theater was closed, especially since the other theater in Salzburg was largely reserved for visiting troupes.

Two long expeditions in search of work interrupted this long Salzburg stay: Mozart and his father visited Vienna from 14 July to 26 September 1773, and Munich from 6 December 1774 to March 1775. Neither visit was successful, though the Munich journey resulted in a popular success with the premiere of Mozart's opera La finta giardiniera.

In August 1777, Mozart resigned his Salzburg position and, on September 23, ventured out once more in search of employment, with visits to Augsburg, Mannheim, Paris and Munich.

Mozart became acquainted with members of the famous orchestra in Mannheim, the best in Europe at the time. He also fell in love with Aloysia Weber, one of four daughters in a musical family. There were prospects of employment in Mannheim, but they came to nothing, and Mozart left for Paris on 14 March 1778 to continue his search. One of his letters from Paris hints at a possible post as an organist at Versailles, but Mozart was not interested in such an appointment. He fell into debt and took to pawning valuables. The nadir of the visit occurred when Mozart's mother took ill and died on 3 July 1778. There had been delays in calling a doctor - probably, according to Halliwell, because of a lack of funds.

While Mozart was in Paris, his father was pursuing opportunities for his son back in Salzburg. With the support of local nobility, Mozart was offered a post as court organist and concertmaster. The yearly salary was 450 florins, but he was reluctant to accept. After leaving Paris on in September 1778, he tarried in Mannheim and Munich, still hoping to obtain an appointment outside Salzburg. In Munich, he again encountered Aloysia, now a very successful singer, but she was no longer interested in him. Mozart finally reached home on 15 January 1779 and took up the new position, but his discontent with Salzburg was undiminished.

Among the better known works that Mozart wrote on the Paris journey are the A minor piano sonata K. 310/300d and the "Paris" Symphony (no. 31); these were performed in Paris on 12 and 18 June 1778.

In January 1781, Mozart's opera Idomeneo premiered with "considerable success" in Munich. The following March the composer was summoned to Vienna, where his employer, Archbishop Colloredo, was attending the celebrations for the accession of Joseph II to the Austrian throne. Mozart, fresh from the adulation he had earned in Munich, was offended when Colloredo treated him as a mere servant and particularly when the archbishop forbade him to perform before the Emperor at Countess Thun's for a fee equal to half of his yearly Salzburg salary. The resulting quarrel came to a head in May: Mozart attempted to resign and was refused. The following month, permission was granted but in a grossly insulting way: the composer was dismissed literally "with a kick in the ass", administered by the archbishop's steward, Count Arco. Mozart decided to settle in Vienna as a freelance performer and composer.

The quarrel with the archbishop went harder for Mozart because his father sided against him. Hoping fervently that he would obediently follow Colloredo back to Salzburg, Mozart's father exchanged intense letters with his son, urging him to be reconciled with their employer. Mozart passionately defended his intention to pursue an independent career in Vienna. The debate ended when Mozart was dismissed by the archbishop, freeing himself both of his employer and his father's demands to return. Solomon characterizes Mozart's resignation as a "revolutionary step", and it greatly altered the course of his life.

Mozart's new career in Vienna began well. He performed often as a pianist, notably in a competition before the Emperor with Muzio Clementi on 24 December 1781, and he soon "had established himself as the finest keyboard player in Vienna". He also prospered as a composer, and in 1782 completed the opera Die Entführung aus dem Serail ("The Abduction from the Seraglio"), which premiered on 16 July 1782 and achieved a huge success. The work was soon being performed "throughout German speaking Europe", and fully established Mozart's reputation as a composer.

Near the height of his quarrels with Colloredo, Mozart moved in with the Weber family, who had moved to Vienna from Mannheim. The father, Fridolin, had died, and the Webers were now taking in lodgers to make ends meet. Aloysia, who had earlier rejected Mozart's suit, was now married to the actor and artist Joseph Lange. Mozart's interest shifted to the third Weber daughter, Constanze. The courtship did not go entirely smoothly; surviving correspondence indicates that Mozart and Constanze briefly separated in April 1782. Mozart also faced a very difficult task in getting his father's permission for the marriage. The couple were finally married on 4 August 1782 in St. Stephen's Cathedral, the day before his father's consent arrived in the mail.

The couple had six children, of whom only two survived infancy:

• Raimund Leopold (17 June – 19 August 1783)
• Karl Thomas Mozart (21 September 1784 – 31 October 1858)
• Johann Thomas Leopold (18 October – 15 November 1786)
• Theresia Constanzia Adelheid Friedericke Maria Anna (27 December 1787 – 29 June 1788)
• Anna Maria (died soon after birth, 25 December 1789)
• Franz Xaver Wolfgang Mozart (26 July 1791 – 29 July 1844)

In the course of 1782 and 1783, Mozart became intimately acquainted with the work of Johann Sebastian Bach and George Frideric Handel as a result of the influence of Gottfried van Swieten, who owned many manuscripts of the Baroque masters. Mozart's study of these scores inspired compositions in Baroque style, and later influenced his personal musical language, for example in fugal passages in Die Zauberflöte ("The Magic Flute") and the finale of Symphony No. 41.

In 1783, Mozart and his wife visited his family in Salzburg. His father and sister were cordially polite to Constanze, but the visit prompted the composition of one of Mozart's great liturgical pieces, the Mass in C minor. Though not completed, it was premiered in Salzburg, with Constanze singing a solo part.

Mozart met Joseph Haydn in Vienna around 1784, and the two composers became friends. When Haydn visited Vienna, they sometimes played together in an impromptu string quartet. Mozart's six quartets dedicated to Haydn (K. 387, K. 421, K. 428, K. 458, K. 464, and K. 465) date from the period 1782 to 1785, and are judged to be a response to Haydn's Opus 33 set from 1781. Haydn in 1785 told Mozart's father: "I tell you before God, and as an honest man, your son is the greatest composer known to me by person and repute, he has taste and what is more the greatest skill in composition."

From 1782 to 1785 Mozart mounted concerts with himself as soloist, presenting three or four new piano concertos in each season. Since space in the theaters was scarce, he booked unconventional venues: a large room in the Trattnerhof (an apartment building), and the ballroom of the Mehlgrube (a restaurant). The concerts were very popular, and the concertos he premiered at them are still firm fixtures in the repertoire. Solomon writes that during this period Mozart created "a harmonious connection between an eager composer - performer and a delighted audience, which was given the opportunity of witnessing the transformation and perfection of a major musical genre".

With substantial returns from his concerts and elsewhere, Mozart and his wife adopted a rather plush lifestyle. They moved to an expensive apartment, with a yearly rent of 460 florins. Mozart also bought a fine fortepiano from Anton Walter for about 900 florins, and a billiard table for about 300. The Mozarts sent their son Karl Thomas to an expensive boarding school, and kept servants. Saving was therefore impossible, and the short period of financial success did nothing to soften the hardship the Mozarts were later to experience.

On 14 December 1784, Mozart became a Freemason, admitted to the lodge Zur Wohltätigkeit ("Beneficence"). Freemasonry played an important role in the remainder of Mozart's life: he attended meetings, a number of his friends were Masons, and on various occasions he composed Masonic music.

Despite the great success of Die Entführung aus dem Serail, Mozart did little operatic writing for the next four years, producing only two unfinished works and the one act Der Schauspieldirektor. He focused instead on his career as a piano soloist and writer of concertos. However, around the end of 1785, Mozart moved away from keyboard writing and began his famous operatic collaboration with the librettist Lorenzo Da Ponte. 1786 saw the successful premiere of The Marriage of Figaro in Vienna. Its reception in Prague later in the year was even warmer, and this led to a second collaboration with Da Ponte: the opera Don Giovanni, which premiered in October 1787 to acclaim in Prague, and also met with success in Vienna in 1788. The two are among Mozart's most important works and are mainstays of the operatic repertoire today, though at their premieres their musical complexity caused difficulty for both listeners and performers. These developments were not witnessed by Mozart's father, who had died on 28 May 1787.

In December 1787, Mozart finally obtained a steady post under aristocratic patronage. Emperor Joseph II appointed him as his "chamber composer", a post that had fallen vacant the previous month on the death of Gluck. It was a part time appointment, paying just 800 florins per year, and required Mozart only to compose dances for the annual balls in the Redoutensaal. However, even this modest income became important to Mozart when hard times arrived. Court records show that Joseph's aim was to keep the esteemed composer from leaving Vienna in pursuit of better prospects.

In 1787 the young Ludwig van Beethoven spent several weeks in Vienna, hoping to study with Mozart. No reliable records survive to indicate whether the two composers ever met.

Toward the end of the decade, Mozart's circumstances worsened. Around 1786 he had ceased to appear frequently in public concerts, and his income shrank. This was a difficult time for musicians in Vienna because Austria was at war, and both the general level of prosperity and the ability of the aristocracy to support music had declined.

By mid 1788, Mozart and his family had moved from central Vienna to the suburb of Alsergrund. Although it has been thought that Mozart reduced his rental expenses, recent research shows that by moving to the suburb, Mozart had certainly not reduced his expenses (as claimed in his letter to Puchberg), but merely increased the housing space at his disposal. Mozart began to borrow money, most often from his friend and fellow Mason Michael Puchberg; "a pitiful sequence of letters pleading for loans" survives. Maynard Solomon and others have suggested that Mozart was suffering from depression, and it seems that his output slowed. Major works of the period include the last three symphonies (Nos. 39, 40, and 41, all from 1788), and the last of the three Da Ponte operas, Così fan tutte, premiered in 1790.

Around this time, Mozart made long journeys hoping to improve his fortunes: to Leipzig, Dresden and Berlin in the spring of 1789, and to Frankfurt, Mannheim and other German cities in 1790. The trips produced only isolated success and did not relieve the family's financial distress.

Mozart's last year was, until his final illness struck, a time of great productivity - and by some accounts a time of personal recovery. He composed a great deal, including some of his most admired works: the opera The Magic Flute; the final piano concerto (K. 595 in B-flat); the Clarinet Concerto K. 622; the last in his great series of string quintets (K. 614 in E-flat); the motet Ave verum corpus K. 618; and the unfinished Requiem K. 626.

Mozart's financial situation, a source of extreme anxiety in 1790, finally began to improve. Although the evidence is inconclusive, it appears that wealthy patrons in Hungary and Amsterdam pledged annuities to Mozart in return for the occasional composition. He probably also benefited from the sale of dance music written in his role as Imperial chamber composer. Mozart no longer borrowed large sums from Puchberg, and made a start on paying off his debts.

He experienced great satisfaction in the public success of some of his works, notably The Magic Flute (performed many times in the short period between its premiere and Mozart's death) and the Little Masonic Cantata K. 623, premiered on 15 November 1791.

Mozart fell ill while in Prague for the 6 September 1791 premiere of his opera La clemenza di Tito, written in that same year on commission for the Emperor's coronation festivities. He was able to continue his professional functions for some time, and conducted the premiere of The Magic Flute on 30 September. The illness intensified on 20 November, at which point Mozart became bedridden, suffering from swelling, pain and vomiting.

Mozart was nursed in his final illness by his wife and her youngest sister, and was attended by the family doctor, Thomas Franz Closset. It is clear that he was mentally occupied with the task of finishing his Requiem. The evidence, however, that he actually dictated passages to his student Süssmayr is minimal.

Mozart died at 1 am on 5 December 1791 at the age of 35. The New Grove gives a matter - of - fact description of his funeral:

Mozart was buried in a common grave, in accordance with contemporary Viennese custom, at the St. Marx Cemetery outside the city on 7 December. If, as later reports say, no mourners attended, that too is consistent with Viennese burial customs at the time; later Jahn (1856) wrote that Salieri, Süssmayr, van Swieten and two other musicians were present. The tale of a storm and snow is false; the day was calm and mild.

The cause of Mozart's death cannot be known with certainty. The official record has it as "hitziges Frieselfieber" ("severe miliary fever", referring to a rash that looks like millet seeds), a description that does not suffice to identify the cause as it would be diagnosed in modern medicine. Researchers have posited at least 118 causes of death, including trichinosis, influenza, mercury poisoning and a rare kidney ailment. The most widely accepted hypothesis is that Mozart died of acute rheumatic fever.

Mozart's modest funeral did not reflect his standing with the public as a composer: memorial services and concerts in Vienna and Prague were well attended. Indeed, in the period immediately after his death, Mozart's reputation rose substantially: Solomon describes an "unprecedented wave of enthusiasm" for his work; biographies were written (first by Schlichtegroll, Niemetschek and Nissen); and publishers vied to produce complete editions of his works.

Mozart's physical appearance was described by tenor Michael Kelly, in his Reminiscences: "a remarkably small man, very thin and pale, with a profusion of fine, fair hair of which he was rather vain". As his early biographer Niemetschek wrote, "there was nothing special about [his] physique. [...] He was small and his countenance, except for his large intense eyes, gave no signs of his genius." His facial complexion was pitted, a reminder of his childhood case of smallpox. He loved elegant clothing. Kelly remembered him at a rehearsal: "[He] was on the stage with his crimson pelisse and gold - laced cocked hat, giving the time of the music to the orchestra." Of his voice his wife later wrote that it "was a tenor, rather soft in speaking and delicate in singing, but when anything excited him, or it became necessary to exert it, it was both powerful and energetic".

Mozart usually worked long and hard, finishing compositions at a tremendous pace as deadlines approached. He often made sketches and drafts; unlike Beethoven's these are mostly not preserved, as his wife sought to destroy them after his death. He was raised a Roman Catholic and remained a member of the Church throughout his life.

Mozart lived at the center of the Viennese musical world, and knew a great number and variety of people: fellow musicians, theatrical performers, fellow Salzburgers, and aristocrats, including some acquaintance with the Emperor Joseph II. Solomon considers his three closest friends to have been Gottfried von Jacquin, Count August Hatzfeld, and Sigmund Barisani; others included his older colleague Joseph Haydn, singers Franz Xaver Gerl and Benedikt Schack, and the horn player Joseph Leutgeb. Leutgeb and Mozart carried on a curious kind of friendly mockery, often with Leutgeb as the butt of Mozart's practical jokes.

He enjoyed billiards and dancing, and kept pets: a canary, a starling, a dog and also a horse for recreational riding. He had a startling fondness for scatological humor, which is preserved in his surviving letters, notably those written to his cousin Maria Anna Thekla Mozart around 1777 – 1778, but also in his correspondence with his sister and parents. Mozart even wrote scatological music, a series of canons that he sang with his friends.

Mozart's music, like Haydn's, stands as an archetype of the Classical style. At the time he began composing, European music was dominated by the style galant, a reaction against the highly evolved intricacy of the Baroque. Progressively, and in large part at the hands of Mozart himself, the contrapuntal complexities of the late Baroque emerged once more, moderated and disciplined by new forms, and adapted to a new aesthetic and social milieu. Mozart was a versatile composer, and wrote in every major genre, including symphony, opera, the solo concerto, chamber music including string quartet and string quintet, and the piano sonata. These forms were not new, but Mozart advanced their technical sophistication and emotional reach. He almost single - handedly developed and popularized the Classical piano concerto. He wrote a great deal of religious music, including large scale masses, but also dances, divertimenti, serenades and other forms of light entertainment.

The central traits of the Classical style are all present in Mozart's music. Clarity, balance, and transparency are the hallmarks of his work, but simplistic notions of its delicacy mask the exceptional power of his finest masterpieces, such as the Piano Concerto No. 24 in C minor, K. 491; the Symphony No. 40 in G minor, K. 550; and the opera Don Giovanni. Charles Rosen makes the point forcefully:

"It is only through recognizing the violence and sensuality at the center of Mozart's work that we can make a start towards a comprehension of his structures and an insight into his magnificence. In a paradoxical way, Schumann's superficial characterization of the G minor Symphony can help us to see Mozart's daemon more steadily. In all of Mozart's supreme expressions of suffering and terror, there is something shockingly voluptuous."

Especially during his last decade, Mozart exploited chromatic harmony to a degree rare at the time, with remarkable assurance and to great artistic effect.

Mozart always had a gift for absorbing and adapting valuable features of others' music. His travels helped in the forging of a unique compositional language. In London as a child, he met J.C. Bach and heard his music. In Paris, Mannheim, and Vienna he met with other compositional influences, as well as the avant - garde capabilities of the Mannheim orchestra. In Italy he encountered the Italian overture and opera buffa, both of which deeply affected the evolution of his own practice. In London and Italy, the galant style was in the ascendent: simple, light music with a mania for cadencing; an emphasis on tonic, dominant, and subdominant to the exclusion of other harmonies; symmetrical phrases; and clearly articulated partitions in the overall form of movements. Some of Mozart's early symphonies are Italian overtures, with three movements running into each other; many are homotonal (all three movements having the same key signature, with the slow middle movement being in the relative minor). Others mimic the works of J.C. Bach, and others show the simple rounded binary forms turned out by Viennese composers.

As Mozart matured, he progressively incorporated more features adapted from the Baroque. For example, the Symphony No. 29 in A major K. 201 has a contrapuntal main theme in its first movement, and experimentation with irregular phrase lengths. Some of his quartets from 1773 have fugal finales, probably influenced by Haydn, who had included three such finales in his recently published Opus 20 set. The influence of the Sturm und Drang ("Storm and Stress") period in music, with its brief foreshadowing of the Romantic era, is evident in the music of both composers at that time. Mozart's Symphony No. 25 in G minor K. 183 is another excellent example.

Mozart would sometimes switch his focus between operas and instrumental music. He produced operas in each of the prevailing styles: opera buffa, such as The Marriage of Figaro, Don Giovanni, and Così fan tutte; opera seria, such as Idomeneo; and Singspiel, of which Die Zauberflöte is the most famous example by any composer. In his later operas he employed subtle changes in instrumentation, orchestral texture, and tone color, for emotional depth and to mark dramatic shifts. Here his advances in opera and instrumental composing interacted: his increasingly sophisticated use of the orchestra in the symphonies and concertos influenced his operatic orchestration, and his developing subtlety in using the orchestra to psychological effect in his operas was in turn reflected in his later non-operatic compositions.

Mozart's most famous pupil, whom the Mozarts took into their Vienna home for two years as a child, was probably Johann Nepomuk Hummel, a transitional figure between Classical and Romantic eras. More important is the influence Mozart had on composers of later generations. Ever since the surge in his reputation after his death, studying his scores has been a standard part of the training of classical musicians.

Ludwig van Beethoven, Mozart's junior by fifteen years, was deeply influenced by his work, with which he was acquainted as a teenager. He is thought to have performed Mozart's operas while playing in the court orchestra at Bonn, and he traveled to Vienna in 1787 hoping to study with the older composer. Some of Beethoven's works have direct models in comparable works by Mozart, and he wrote cadenzas (WoO 58) to Mozart's D minor piano concerto K. 466.

A number of composers have paid homage to Mozart by writing sets of variations on his themes. Beethoven wrote four such sets (Op. 66, WoO 28, WoO 40, WoO 46). Others include Frédéric Chopin's Variations on "Là ci darem la mano" from Don Giovanni (1827); Max Reger's Variations and Fugue on a Theme by Mozart (1914), based on the variation theme in the piano sonata K. 331; Fernando Sor's Introduction and Variations on a Theme by Mozart (1821); and Mikhail Glinka's Variations on a Theme from Mozart's Opera Die Zauberflöte in E♭ major (1822). Pyotr Ilyich Tchaikovsky wrote his Orchestral Suite No. 4 in G, "Mozartiana" (1887), as a tribute to Mozart.

For unambiguous identification of works by Mozart, a Köchel catalog number is used. This is a unique number assigned, in regular chronological order, to every one of his known works. A work is referenced by the abbreviation "K." followed by this number. The first edition of the catalog was completed in 1862 by Ludwig von Köchel. It has since been repeatedly updated, as scholarly research improves knowledge of the dates and authenticity of individual works.