The document discusses various HTML tags used to structure and layout web pages. It describes common tags like <html>, <head>, <body>, <p>, <a>, <img>, <br>, <b>, <i>, <u>, <hr>, <sub>, <sup>, <pre>, <div>, <span>, <ul>, <ol>, <li>, <table>, <tr>, <td>, <th>, and <form>. It explains the purpose and usage of each tag with examples.