An étude (literally "study" in Fr.) can either be a technical study for instrument or a concert piece which emphasizes technicality.
The first études were composed very early on and were commonly vocal solfeggi and keyboard works. The Italian composer Girolamo Diruta (c.1554-after 1610) included some of the earliest examples of the étude in his treatise Il transilvano. Around the late 18th Century the first collections of études were published. With the piano études by Frederic Chopin (Opus 10, 1833; Opus 25, 1837), the étude became a composition of considerable musical interest apart from its merit as a technical study.
Noted étude composers
The below list of composers have all added to the repertoire:
- Girolamo Diruta (c.1554-after 1610)
- Franz Wohlfahrt(1833–1884): wrote 60 Studies for Violin (Op. 45)
- Rodolphe Kreutzer (1766–1831): for the violin
- Lillian Fuchs (1903-91): for the viola
- Friedrich Grützmacher (1832-1903): for the violoncello
- Frédéric Chopin (1810–1849): wrote 24 études in two sets of 12 études each (Opp. 10 and 25), plus three more.
- Carl Czerny (1791–1857)
- Henri Bertini (1798–1876): wrote 24 études (Op. 29)
Today, the idea of an étude can be up to the individual composer his/herself. Modern works range from Messians' "Four studies in rhythm" (which experiments with serial durations and rhythm) to Cages' Freedom Etudes for violin (which are aleatoric works based on star charts.) There is no set form for composing an étude.
-Encyclopedia Brittanica [www.britannica.com/EBchecked/topic/194671/etude]
-Dolmetsch Online Music Dictionary 
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