He was the son of a professional violinist who played at St. Mark's and may have been involved in operatic management. Vivaldi was trained for the priesthood and ordained in 1703 but soon after his ordination ceased to say Mass. He claimed this was because of his unsure health (he is known to have suffered from chest complaints, possibly asthma or angina). In 1703 he was appointed "maestro di violino" at the Ospedale della Pietà, one of the Venetian girls' orphanages; he remained there until 1709, and held the post again, 1711-16; he then became "maestro de' concerti". Later, when he was away from Venice, he retained his connection with the Pietà (at one period he sent two concertos by post each month). He became "maestro di cappella", 1735-8; even after then he supplied concertos and directed performances on special occasions.
Vivaldi's reputation had begun to grow with his first publications: trio sonatas (probably 1703-5), violin sonatas (1709) and especially his 12 concertos "L'estro armonico" op.3 (1711). These, containing some of his finest concertos, were issued in Amsterdam and widely circulated in northern Europe; this prompted visiting musicians to seek him out in Venice and in some cases commission works from him (notably for the Dresden court). Bach transcribed five op.3 concertos for keyboard, and many German composers imitated his style. He published two further sets of sonatas and seven more of concertos, including "La stravaganza" op.4 (circa 1712), "Il cimento dell'armonia e dell'inventione" (circa 1725, including 'The Four Seasons') and "La cetra" (1727). It is in the concerto that Vivaldi's chief importance lies. He was the first composer to use ritornello form regularly in fast movements, and his use of it became a model; the same is true of his three-movement plan (fast-slow-fast). His methods of securing greater thematic unity were widely copied, especially the integration of solo and ritornello material; his vigorous rhythmic pattems, his violinistic figuration and his use of sequence were also much imitated.
Of his circa 550 concertos, circa 350 are for solo instrument (more than 230 for violin); there are circa 40 double concertos, more than 30 for multiple soloists and nearly 60 for orchestra without solo, while more than 20 are chamber concertos for a small group of solo instruments without orchestra (the 'tutti' element is provided by the instmments all playing together). Vivaldi was an enterprising orchestrator, writing several concertos for unusual combinations like viola d'amore and lute, or for ensembles including chalumeaux, clarinets, horns and other rarities. There are also many solo concertos for bassoon, cello, oboe and flute. Some of his concertos are programmatic, for example 'La tempesta di mare' (the title of three concertos). Into this category also fall 'The Four Seasons', with their representation of seasonal activities and conditions accommodated within a standard ritornello form - these are described in the appended sonnets, which he may have written himself.
Vivaldi was also much engaged in vocal music. He wrote a quantity of sacred works, chiefly for the Pietà girls, using a vigorous style in which the influence of the concerto is often marked. He was also involved in opera and spent much time travelling to promote his works. His earliest known opera was given in Vicenza in 1713; later he worked at theatres in Venice, Mantua (1718-20), Rome (probably 1723-5), possibly Vienna and Prague (around 1730), Ferrara (1737), Amsterdam (1738) and possibly Vienna during his last visit. He was by most accounts a difficult man; in 1738 he was forbidden entry to Ferrara ostensibly because of his refusal to say Mass and his relationship with the singer Anna Giraud, a pupil of his with whom he travelled. More than 20 of his operas survive; those that have been revived include music of vitality and imagination as well as more routine items. But Vivaldi's importance lies above all in his concertos, for their boldness and originality and for their central place in the history of concerto form.