The document discusses HTML (Hyper Text Markup Language) and its basic elements and tags. It explains that HTML uses tags to tell browsers how to display elements on a web page. The two main types of tags are container tags, which have opening and closing tags to affect everything within, and empty tags, which only have an opening tag and carry out a specific task. It provides examples of common tags like <head>, <body>, <title>, <h1-6> for headings, <p> for paragraphs, <br> for line breaks, and lists <ul>, <ol>, and <li>.