Variation is a form that is an altered version of a given theme, diverging from it by melodic ornamentation and by changes in harmony, rhythm, or key.
Variation, sheet music:
Air with Variations in F major (George Frideric Handel)
VARIATIONS on a Scottish Theme (Mikhail Glinka)
VARIATIONS on Alyabyev’s Song “THE NIGHTINGALE” (Mikhail Glinka)
VARIATIONS on a Russian Theme (Mikhail Glinka)
VARIATIONS ON A RUSSIAN SONG (Isaak Yakovich Berkovich)
VARIATIONS on the theme of the Belarusian folk song PEREPELOCHKA (Isaak Yakovich Berkovich)
VARIATION on the theme of Russian folk song (N. Lyubarskii)