The term "Impromptu" originates from Latin, meaning "unprepared." It is said that the word was first used by two composers simultaneously and coincidentally in their own works in 1822. As a musical genre, the impromptu has little relation to improvisation as a performance technique. It simply refers to a piece of music that reflects an improvisatory atmosphere, and it is a musical genre that emerged in the 19th century or later (although the idea of improvisatory music itself is by no means unique to the 19th century, it was previously known by various names such as toccata and capriccio).

In the first half of the 19th century, the tradition of the impromptu largely followed two main streams. One stream involved continuous variations on popular opera arias or folk melodies, exemplified by works from Czerny, Kalkbrenner, and even some fine pieces by Liszt. The other stream consisted of lyrical musical content without a specific form, represented by the impromptus of Voříšek and Marschner, who are said to have first used the term, as well as Schubert’s impromptus. However, even if the form is not fixed, many of them adopt an A-B-A arch form.

Chopin inherited the tradition linked to Schubert, leaving behind the Fantaisie-Impromptu and three Impromptus during his middle creative period. All of them have a clear arch form, with the middle section designated as "sostenuto."

Impromptu No. 3

Impromptu No. 3 employs a technique largely similar to that of No. 1, forming a typical example of Chopin's Impromptus. These include perpetual motion triplets, displaced accents, and frequently used appoggiaturas. In No. 3, a new technique is introduced: manipulating the sense of tempo through variations in textural density.

Furthermore, the theme of Impromptu No. 1 and the introductory melody of No. 3 suggest a certain connection. Viewed in this light, it is also possible to find melodic connections across all four Impromptus. For instance, the melodic framework of the Sostenuto theme in No. 1, the opening theme of No. 2, and the melody appearing in the Sostenuto section of the Fantaisie-Impromptu are clearly similar. However, it cannot be confirmed that Chopin was aware of these connections, and even if they were intentional, they are likely nothing more than a composer's playful touches. This is because the four Impromptus possess strong individual independence and do not form a continuous cycle of pieces.