This document discusses Cascading Style Sheets (CSS) and Dynamic HTML (DHTML). CSS allows for controlling the style and layout of HTML documents, including visual elements like colors, fonts, and formatting. CSS separates design from structure. Some advantages of CSS include saving time, faster page loads, and easier maintenance compared to HTML. DHTML refers to dynamically rendering HTML content using client-side scripting and the Document Object Model. The document then provides examples of embedding, externally linking, and importing CSS stylesheets to style HTML pages.