The document summarizes information presented at the 11th Thailand Open Source Software Festival about HTML5 and building templates for Joomla!. It provides an overview of HTML5, describing it as the new standard for HTML, how it has evolved since HTML 4.01 in 1999, and how major browsers now support many of its new elements and APIs. It also discusses building Joomla! templates, including template structure, using HTML5 elements and enabling scripts, CSS3 features like @font-face, vendor prefixes, and frameworks that support HTML5. Finally, it covers key HTML5 features for mobile devices and showcasing Joomla! templates on mobile.