The document provides an analogy comparing the structure of a human body to the structure of web pages. It states that HTML provides the skeleton-like structure and tags that act as placeholders for content, similar to how a human body has an internal structure and organs. CSS is then compared to makeup, allowing adjustments to attributes like color, height, and size. Finally, JavaScript is likened to the human nervous system, enabling actions, reactions, and computations on web pages just as the nervous system facilitates activities in the human body.