The document discusses the three layers of web design: structure with HTML, style with CSS, and behavior with JavaScript. It provides examples of how each layer contributes to building a web page, with HTML providing structure and markup, CSS controlling presentation and styling, and JavaScript adding interactivity and dynamic behavior. The document also seeks to clarify that JavaScript is not the same as Java, as their names often cause confusion, and outlines some common uses of JavaScript like form validation, auto-suggest search functionality, and slideshow creation.