The Chopin nocturnes constitute 21 pieces for solo piano written by Frédéric Chopin between 1827 and 1846. They are generally considered among the finest short solo works for the instrument and hold an important place in contemporary concert repertoire. Although Chopin did not invent the nocturne, he popularized and expanded on it, building on the form developed by Irish composer John Field.Chopin's nocturnes numbered 1 to 18 were published during his lifetime, in twos or threes, in the order of composition. However, numbers 19 and 20 were actually written first, prior to Chopin's departure from Poland, but published posthumously. Number 20 was not originally entitled "nocturne" at all, but since its publication in 1870 as such, it is generally included with publications and recordings of the set.