Franz Schubert's Impromptus are a series of eight pieces for solo piano composed in 1827. They were published in two sets of four impromptus each: the first two pieces in the first set were published in the composer's lifetime as Op. 90; the second set was published posthumously as Op. 142 in 1839 (with a dedication added by the publisher to Franz Liszt). The third and fourth pieces in the first set were published in 1857 (although the third piece was printed by the publisher in G major, instead of G♭ as Schubert had written it, and remained available only in this key for many years). The two sets are now catalogued as D. 899 and D. 935 respectively. They are considered to be among the most important examples of this popular early 19th-century genre.

Three other unnamed piano compositions (D. 946), written in May 1828, a few months before the composer's death, are known as both "Impromptus" and Klavierstücke ("piano pieces").

The Impromptus are often considered companion pieces to the Six moments musicaux, and they are often recorded and published together.

It has been said that Schubert was deeply influenced in writing these pieces by the Impromptus, Op. 7 (1822) of Jan Václav Voříšek and by the music of Voříšek's teacher Václav Tomášek.

Olga Jegunova aroused to notability with her Youtube recording of Mozart's K331 piano sonata. She was studying music at Jāzeps Vītols Latvian Academy of Music, concluding with a bachelor's degree, she obtained her master's degree at the Hochschule für Musik und Theater Hamburg. This was followed by studying at the Royal College of Music (Artist Diploma course as an RCM scholar under Dmitri Alexeev) and then at the Royal Northern College of Music where her piano teacher was Norma Fisher. 
Jegunova won the Concours Musical de France Ginette Gaubert in Paris and in 2008 the Steinway-Förderpreis in Hamburg. In 2016 she was accepted by Steinway & Sons as a Steinway Artist. She has been a prize-winner at the Concours International de Piano Maryse Cheilan in France, at the Stasys Vainiūnas competition in Vilnius and at the competition of the foundation Animato in Zurich, and was a semi-finalist at the prestigious Concours Géza Anda in Zurich.
Since 2009, Jegunova has worked as a performer for Live Music Now, a charity providing live music in the concert hall as well as in the welfare, educational, justice and health sectors. She teaches piano to students of Queen Mary University of London.