Which musical form consists of a main theme followed by altered renditions?

The musical form that consists of a main theme followed by altered renditions is theme and variations. In this structure, the initial theme is presented and then transformed in subsequent sections through various techniques such as changing the harmony, rhythm, melody, or instrumentation. Each variation maintains some recognizability of the original theme while introducing new elements, allowing for creative exploration.

This approach is notably prevalent in various genres, allowing composers to showcase their creativity and the thematic material's flexibility. The variations can range from subtle changes to significant reworking, providing a rich listening experience. Through this structure, the listener can appreciate the original theme's integrity while enjoying the diversity that each variation brings. Other forms mentioned, such as sonata form, binary form, and canzona, follow different structural paradigms and do not focus primarily on the principle of alternating a single theme with variations.