Which literary element refers to the underlying message or main idea of a work?

The term that refers to the underlying message or main idea of a work is theme. Theme is the central concept or idea that the author explores throughout the narrative, often conveying insights or reflections on life, society, or human nature. It acts as a guiding framework that shapes the story and enriches the reader's understanding of the text.

In contrast, characterization pertains to how an author develops and reveals the personalities, motives, and qualities of the characters within the story, focusing on their traits and evolution. Plot is concerned with the sequence of events and actions that comprise the storyline, detailing how the conflict unfolds and resolves. Setting encompasses the time and place in which the story occurs, providing the backdrop that influences the characters and events but does not in itself encapsulate the underlying message of the work.