What is the term for adding brief notes or explanations to a diagram?

The term for adding brief notes or explanations to a diagram is "annotate." This process enhances the viewer's understanding by providing context or additional information directly related to specific elements in the diagram. Annotations can clarify the purpose or function of the different parts represented, making the information more accessible and informative. It is commonly used in educational settings to help explain complex diagrams, making them easier to interpret and study.

Labeling refers specifically to the act of naming or identifying parts of a diagram, which does not necessarily provide additional explanatory notes. Illustrating typically involves creating or producing visuals to represent ideas, and while a diagram itself is a type of visual representation, it does not imply the act of adding notes. Thus, annotate best captures the action of adding explanatory notes to enhance understanding.