Swan Lake, Op. 20, is a ballet composed by Russian composer Pyotr Ilyich Tchaikovsky in 1875–76. Despite its initial failure, it is now one of the most popular of all ballets.

The scenario, initially in two acts, was fashioned from Russian and German folk tales and tells the story of Odette, a princess turned into a swan by an evil sorcerer's curse. The choreographer of the original production was Julius Reisinger (Václav Reisinger). The ballet was premiered by the Bolshoi Ballet on 4 March [O.S. 20 February] 1877 at the Bolshoi Theatre in Moscow. Although it is presented in many different versions, most ballet companies base their stagings both choreographically and musically on the 1895 revival of Marius Petipa and Lev Ivanov, first staged for the Imperial Ballet on 15 January 1895, at the Mariinsky Theatre in St. Petersburg. For this revival, Tchaikovsky's score was revised by the St. Petersburg Imperial Theatre's chief conductor and composer Riccardo Drigo.

There is no evidence to prove who wrote the original libretto, or where the idea for the plot came from. Russian and German folk tales have been proposed as possible sources, including "The Stolen Veil" by Johann Karl August Musäus, but both those tales differ significantly from the ballet.

One theory is that the original choreographer, Julius Reisinger, who was a Bohemian (and therefore likely to be familiar with "The Stolen Veil"), created the story. Another theory is that it was written by Vladimir Petrovich Begichev, director of the Moscow Imperial Theatres at the time, possibly with Vasily Geltser, danseur of the Moscow Imperial Bolshoi Theatre (a surviving copy of the libretto bears his name). Since the first published libretto does not correspond with Tchaikovsky's music in many places, one theory is that the first published version was written by a journalist after viewing initial rehearsals (new opera and ballet productions were always reported in the newspapers, along with their respective scenarios).

Some contemporaries of Tchaikovsky recalled the composer taking great interest in the life story of Bavarian King Ludwig II, whose life had supposedly been marked by the sign of Swan and could have been the prototype of the dreamer Prince Siegfried.

Begichev commissioned the score of Swan Lake from Tchaikovsky in May 1875 for 800 rubles. Tchaikovsky worked with only a basic outline from Julius Reisinger of the requirements for each dance. Unlike the instructions for the scores of The Sleeping Beauty and The Nutcracker, none of the original written instruction was thought to have survived. Most of what scholars knew about information such as choreography came from gossip and reviews of the performance. However, rehearsal notes dating as early as 1876 have been recently discovered in the Institute for Art Studies in Moscow, revealing more information about what the original 1877 production may have looked like.

Read more: https://en.wikipedia.org/wiki/Swan_Lake