HTML Elements are made up of the start tag, end tag and content between these tags. HTML structure and page layouts are build using elements.
As you show in the above structure, HTML is the root element and all other elements reside within this element.
Within HEAD Element, we can define TITLE, STYLE, SCRIPT, META, BASE Elements. These tags contain information about the page and link to the external resources.
The content section resides within the BODY Element. BODY Element contains document's heading, paragraph, table, image, multimedia and other elements that are visible on the web page.