Frédéric Chopin's four ballades are single-movement pieces for solo piano, composed between 1831 and 1842. They are considered to be some of the most challenging pieces in the standard piano repertoire. The term ballade was used by Chopin in the sense of a balletic interlude or dance-piece, equivalent to the old Italian ballata, but the term may also have connotations of the medieval heroic ballad, a narrative minstrel-song, often of a fantastical character. There are dramatic and dance-like elements in Chopin's use of the genre, and he may be said to be a pioneer of the ballade as an abstract musical form. The four ballades are said to have been inspired by poet Adam Mickiewicz. The exact inspiration for each individual ballade, however, is unclear and disputed.