Short answers, pulled from the story.
The Salzburg Festival was officially inaugurated on the 22nd of August 1920 with a performance of Hugo von Hofmannsthal's play Jedermann on the steps of Salzburg Cathedral. The organizing body, the Salzburger Festspielhaus-Gemeinde, had been formed in 1917 by Friedrich Gehmacher and Heinrich Damisch.
The five founders are the poet Hugo von Hofmannsthal, the composer Richard Strauss, the scenic designer Alfred Roller, the conductor Franz Schalk, and the director Max Reinhardt. They championed the festival's creation at the close of the First World War in 1918.
The festival continued under Nazi rule after the 1938 Anschluss, though Arturo Toscanini resigned in protest and Jewish artists including Max Reinhardt and Georg Solti were forced to emigrate. It was finally cancelled in 1944 by order of Reich Minister Joseph Goebbels and reopened in the summer of 1945 immediately after Allied victory.
Jedermann, or Everyman, is a play by Hugo von Hofmannsthal, one of the festival's founders. It was first performed at the Salzburg Cathedral steps on the 22nd of August 1920 in a production directed by Max Reinhardt and has been performed at Cathedral Square every year since, making it the festival's most enduring tradition.
The festival reported in 2017 that it directly and indirectly creates about 183 million euros in value for Salzburg each year, with ticket sales of roughly 27 million euros. It sustains approximately 2,800 full-time equivalent jobs in Salzburg and provides the public sector with around 77 million euros in taxes and duties.
Since 2012, the artistic director of the Salzburg Whitsun Festival has been the Italian mezzo-soprano Cecilia Bartoli, who also performs as the female lead. The Whitsun Festival was originally created by Herbert von Karajan in 1973 and has been organized by the Salzburger Festspielfonds since 1998.