Themes play a crucial role in creating musical coherence and unity. They often recur in different sections of a musical form, such as variations, sonatas, concertos, operas, and symphonies. The thematic material may undergo transformations through alterations in harmony, rhythm, orchestration, or key, contributing to the development and progression of the piece.
A theme serves as a point of reference, providing familiarity and coherence for the listener despite the unfolding complexities of the music. Many famous compositions can be recognized and characterized by their iconic and memorable themes.