Chopin's "Études" (studies) are some of the hardest pieces of all the works in concert piano repertoire. Because of this, the music remain famous and are often played at concerts. Some of them have been given nicknames (but not by Chopin himself) - for example, the last "Étude" from Op. 10 has been called the "Revolutionary" because it was inspired by the November 1830 Uprising, when the Poles were defeated by the Russian Empire.