The document discusses 5 essential meta tags for optimizing a website for Google:
1. The DTD statement which allows for faster and deeper indexing with Google.
2. The title tag which is the most important as it is what is displayed in search results and influences clicks.
3. The description tag which Google uses to describe the page if included.
4. The keywords tag which Google actually uses against sites so niche keywords should go in content, not here.
5. The charset type tag which tells browsers how to handle characters for faster indexing with the 8859-1 tag.