Animpromptu (/ɪmˈprɒmptjuː/, French:[ɛ̃pʁɔ̃pty], loosely meaning "offhand") is a free-form musical composition with the character of an ex tempore improvisation as if prompted by the spirit of the moment, usually for a solo instrument, such as piano. According to Allgemeine musikalische Zeitung, Johann Baptist Cramer began publishing piano pieces under the (sub-)title of "impromptu." (AMZ, Mar. No II, 1815, col. 6), which seems to be the first recorded use of the term impromptu in this sense.
Since the very concept of unpremeditated, spur-of-the-moment inspiration without studied care is at the heart of Romantic artistic theory, it did not take long before the first generation of Romantic composers took up the idea. Others were:
Jan Václav Voříšek was the first one to compose impromptus published under that title, in 1822.
Franz Schubert published two sets of four Impromptus for piano, Op. 90 and Op. 142 (1827). After his death three more unnamed piano compositions (Klavierstücke) were sometimes named Impromptus.
Robert Schumann wrote some Impromptus, published as Op. 5 (1833).
Charles-Valentin Alkan composed two sets of four Impromptus, published as Op. 32 (No. 1 in 1848, and No. 2 in 1849).
Franz Liszt composed an Impromptu in F sharp (sometimes called Nocturne) and a piano piece named Valse-Impromptu.
Alexander Scriabin is known to have written at least nine impromptus for the piano in his early period.
Jean Sibelius composed six impromptus for piano op. 5 (1893)
The impromptu genre remained popular all throughout the 19th century and was prominent throughout the romantic era.
In the 20th century, there are also several examples of composers naming their compositions "Impromptu", such as:
Gabriel Fauré composing six Impromptus between 1881 and 1913.
