Rhetoric is the way we use communication (e.g., language, images, sound, etc.) to persuade. Overall, it’s how a text says something (or how it performs), and the speaker/writer adapts their text/message depending on their purpose and target audience. When approaching rhetoric, one popular way to explain how it works is to use the rhetorical triangle, which shows what is called the rhetorical situation.
Multimodal rhetoric refers to the combination of different “modes” of communication (writing, sound, images, code, etc.).