Theme (music) Wikipedia open wikipedia design. In music, a theme is the beginning or primary melody. It is usually familiar sounding and able to be recognized when it is heard. From that beginning part of the music, variations can be played as the composition is developed or put together. This short article about music can be made longer. You can help Wikipedia by adding to it. This page is based on a Wikipedia article written by contributors (read/edit).Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.