The document provides a reference guide for HTML5 tags including the tag name, which HTML versions the tag is valid for, and common attributes for each tag. It lists over 100 tags across 4 pages, providing brief descriptions and allowed attributes for each. Key tags covered include common text tags like <p>, <strong>, and <em>, media tags like <audio> and <video>, form tags like <button> and <input>, semantic sectioning tags like <header> and <footer>, and lists tags like <ul> and <ol>.