Short answers, pulled from the story.
Orpheus was a Thracian bard, legendary musician, poet, and prophet in Greek mythology. Pindar called him "the father of songs" and identified him as the son of the Thracian king Oeagrus and the Muse Calliope. He was credited with music powerful enough to charm animals, move rocks and trees, and even influence the gods of the underworld.
Eurydice was bitten by a viper on her wedding day after fleeing a satyr into tall grass. Orpheus descended into the underworld to retrieve her, and Hades and Persephone agreed to release her on condition that he not look back until both had reached the upper world. He turned too soon, and she vanished forever.
Orpheus was torn apart by Thracian Maenads, followers of Dionysus. According to Aeschylus's lost play Bassarids, Dionysus sent them because Orpheus had abandoned the worship of all gods except Apollo. His severed head floated down the River Hebrus to the island of Lesbos, where it continued to prophesy until Apollo silenced the oracle.
The Derveni papyrus, found in Derveni, Macedonia in 1962, is Europe's oldest surviving manuscript, dating to around 340 BC during the reign of Philip II of Macedon. It contains an allegorical philosophical commentary on an Orphic poem, a theogony concerning the birth of the gods produced in the circle of the philosopher Anaxagoras.
The Orphic way of life, known as Orphikos bios, was a religious practice followed by devotees of Orphic poetry. It required vegetarianism, abstention from sex, and refusal to eat eggs and beans. Followers used hexametric poems attributed to Orpheus as their religious authority, and participated in mystery-rites and purification rituals.
Major works include Jacopo Peri's Euridice (1600), Monteverdi's L'Orfeo (1607), Gluck's Orfeo ed Euridice (1762), Offenbach's Orphee aux Enfers (1858), Stravinsky's ballet Orpheus (1948), Birtwistle's The Mask of Orpheus (completed 1984), and Anaïs Mitchell's Hadestown, which reached Broadway in 2019 and won multiple Tony Awards.