Basicly, HTML sitemaps- normal sitemap on your websie with links to your important pages. Good for humans and for search engines. XML sitemaps - good for search engines You can get an introduction (explanation + code examples) of all sitemap file formats here: http://www.microsystools.com/products/sitemap-generator/help/website-sitemap-kinds-comparison/ (including RSS versus ROR versus XML versus XHTML versus HTML which people often confuse)