Header Element in HTML5
The header element represents the header of a section. It’s meant to be used as a container for a group of introductory content or set of navigational links.
While most websites currently have one header at the top of the page as a masthead, you can have multiple headers in a single html5 document. Usually you would use the header tag at the top of a document (as a masthead) or at the top of a section of content.
Getting used to multiple headers will probably be the most difficult adjustment.