This document provides an introduction to HTML, CSS, and JavaScript for building websites. It discusses how websites work by connecting clients and servers, and compares making a website to writing a book by organizing content into pages. The document then covers the basic purposes and syntax of HTML for creating page content, CSS for styling, and JavaScript for interactivity. It provides many code examples and explains common elements, properties, and methods in each language to demonstrate basic front-end web development concepts and tools.