Short answers, pulled from the story.
The Poetic Edda is a collection of anonymous Old Norse poems preserved primarily in the 13th-century Icelandic manuscript known as the Codex Regius. It is considered arguably the most important surviving source on Norse mythology and Germanic heroic legend, and has shaped Scandinavian literature since the early 19th century.
The Codex Regius was unknown to scholars until 1643, when it came into the possession of Bishop Brynjólfur Sveinsson of Skálholt. It was stored in the Royal Library in Copenhagen for centuries before being returned to Iceland in 1971, transported by ship with a naval escort.
None of the Eddic poems are attributed to a particular author. They were passed orally from singer to singer for centuries before being written down. Bishop Brynjólfur attributed the Codex Regius to Sæmundr the Learned, a 12th-century Icelandic priest, but modern scholars reject that attribution.
Most poems are composed in fornyrðislag (old story metre), with málaháttr (speech form) as a common variation. About a quarter of the poems use ljóðaháttr (song form). All three metres are stress-based and use alliteration rather than end rhyme.
Tolkien drew on the Poetic Edda directly in multiple works. The Misty Mountains in The Hobbit derive from the úrig fiöll in Skírnismál, and the names of his Dwarves come from the Dvergatal in Völuspá. His Legend of Sigurd and Gudrún is a verse retelling of the Niflung poems composed in the Eddic fornyrðislag metre.
The earliest printed English translation was produced by A. S. Cottle in 1797, though some short sections had been translated as early as the 1670s. Cottle relied partly on a Latin translation and his version is now considered very inaccurate. The most recent translation, by Edward Pettit, was published in 2023.