Who they were
Antonio Vivaldi was a Venetian composer and violin virtuoso, ordained a priest in 1703 and nicknamed the Red Priest for his hair. For most of his career he taught the violin and directed music at the Ospedale della Pietà, a Venetian home for orphaned and abandoned girls famous for its all-female orchestra.
What they did
He wrote around 500 concertos, fixing the fast–slow–fast three-movement form and the ritornello structure that later composers built on; the set L’estro armonico (1711) spread his style across Europe, and Johann Sebastian Bach transcribed several of its concertos. The Four Seasons, four violin concertos published in 1725 with sonnets describing the scenes the music paints, is his most famous work, and he also wrote sacred music such as the Gloria and dozens of operas.
Legacy
His fame faded in his own lifetime; he moved to Vienna in 1740 and died there poor a year later. After his manuscripts resurfaced in Turin in the 1920s his music was revived, and The Four Seasons is now among the most performed works in all of classical music.