The document discusses the 3 layers of a web page: content (HTML), presentation (CSS), and behavior (JavaScript). It states that the content layer defines the structure and semantics, the presentation layer specifies the visual design, and the behavior layer adds interactivity. It provides examples of using HTML tags like <h1>, <p>, and <ul> to build the content layer and separates the different layers to build a webpage like building a house with different materials.