Although every musical work relies on variations techniques to develop musical ideas, there are genres that are formally structured by the variation concept. We can distinguish two main types of variations: sectional and continuous.
In sectional variations, a brief theme - sometimes borrowed from another composer - is followed by variations. A final barline indicates the end of the theme and each variation. Less common cases present the theme at the end of the variations (Britten, Nocturne for guitar on a John Dowland song) or the theme appears before and after the variations (Bach, Golberg Variations).
Continuous variations are based on a short harmonic pattern repeated numerous times. We find examples of continuous variations in dances such as the chaconne and the passacaglia.