Der Ring Des Nibelungen is an operatic tetralogy of stage festival plays or musical dramas, composed (music and verse) by Richard Wagner, based on ancient Norse and Germanic legends of the Gods, the Walsungs, and the Ring of Alberich the Dwarf.
Wagner wrote the libretto and music over the course of about twenty-six years, from 1848 to 1874, leading to their first performances as part of the cycle in his purpose-built theater in Bayreuth in 1876 nearly thirty years after their inception.
The work is written in the style of Goethe and Shakespeare, and influenced by philosophers of its day like Hegel, Proudhon and Feuerbach and, eventually, Schopenhaur. It is one of Wagner's most well-known pieces, alongside the likes of Tristan und Isolde.
The story concerns four main characters: Alberich, king of the Dwarfs; Wotan, his rival and king of the Gods; Brunnhilde, Wotan's daughter, and Siegfried, her lover. It begins with Alberich stealing magic gold to forge the Ring that would give him the power to rule the world, which is promptly stolen by Wotan and given under duress to the giant Fafner. Since Wotan is the god of laws, he cannot take the Ring from Fafner without breaking his rules and losing his power but, fearing Alberich will attain it first, sires in secret the Walsung Siegmund, who he's later forced to let die, but not before he and his twin sister Sieglinde sire Siegfried. For trying to abay Siegmund's sentence, Wotan's daughter Brunnhilde is punished to be left asleep on a high mountain, where only Siegfried can come to her rescue, which he does after obliviously slaying Fafner for the Ring. Years later, Siegfried is led astray by Alberich's son Hagen, and the betrayed Brunnhilde aids in the conspiracy of his death, but in her final moments realizes the deception, takes the Ring and, in her own funeral pyre, has it purified and returned to the Rhine, before she and the gods up in Valhalla perish.
Wagner first concieved of the Ring as a single opera following Lohengrin: he had been reading materials about the Nibelung myth (which concerns the scenario of Lohengrin) since 1844, but didn't concieve of writing a Nibelung-themed opera until 1848 when he composed a libretto of Siegfried's Tod (Siegfried's Death), along with a prose scenario that detailed much of the backstory that would become the complete Ring. He wrote additional studies on the sagas and about the new musical form he envisioned for it, touched-up his libretto and even started composing music for the prologue and musing on building a theater ideal for the performance of the work.
At that point, however, he was motivated to write a libretto for a prequel, Jung-Siegfried (Young Siegfried), which told of Siegfried's youth, including the slaying of Fafner and awakening of Brunnhilde, as a comedic counterpart to the tragedy of Siegfried's Tod. He sketched some musical ideas, but soon came to realize the backstory of Siegmund and Wotan was also necessary to render on the stage, concieving of Die Walkure and then of Das Rheingold as a "prelude" or "perliminary evening" and beginning to sketch them simultaneously. Wagner continued to regard the Ring as a trilogy with a prelude, rather than a tetralogy.
With the poems of Rhinegold and Walkure complete, and those of Siegfried and Gotterdamerung (as the later two operas were now renamed) revised, Wagner began composing the music beginning with Rhinegold. Along the way, he had to commission the creation of new instruments like the Wagner Tuba, Bass Trumpet and Contrabass Trombone.
When he finished act two of Siegfried, he laid down the project for twelve years in favour of Tristan und Isolde, La Tannhauser, Die Meistersingers von Nurmberg and some early work on Parsifal, before he returned to orchestrate Siegfried and complete its third act, as well as a related chamber orchestra piece, the Siegfried Idyll. He then completed Gotterdamerung, and proceeded to build the Bayreuth theater, and work on the rehearsals for the complete cycle.