A strophic form in music represents the repetition of a section of music where each repeat has the same basic melody, harmony and rhythm. In modified strophic form, the repeated sections of music have varied or elaborated forms from the basic theme.
According to AEIOU, strophic form in music has similarity across all its verses, whereas modified strophic form has variation on individual stanzas. Maestros of the Guitar describes strophic form as having a musical pattern of "A, A, A..." where "A" represents a musical section; modified strophic form, on the other hand, follows a pattern of "A, A', A''..." etc.
Some songs commonly utilizing strophic form include many 12-bar blues, ballads, hymns and chants, and the 17th-century French "Air de cour." Some songs that utilize modified strophic form include Schubert's "Des Baches Wiegenlied," "Du bist die Ruh" and "Der Lindenbaum."