This document introduces HTML, CSS, and JavaScript for building websites. It defines HTML as the standard markup language used to describe web page structure using elements like headings, paragraphs, and links. CSS is described as controlling how HTML elements are displayed on different mediums, and can format multiple pages at once through external style sheets. JavaScript is introduced as the most popular programming language that can modify HTML and CSS, and is commonly used for web interactions, animations, and effects. The document encourages the reader to ask any questions and looks forward to helping them learn inside.