The <header> element represents a container for introductory content or a set of navigational links.
A <header> element typically contains:
one or more heading elements (<h1> - <h6>)
logo or icon
authorship information
You can have several <header> elements in one document.
SIDE-BAR
The <aside> tag defines some content aside from the content it is placed in. The aside content should be related to the surrounding content.
FOOTER
The <footer> tag defines a footer for a document or section.
A <footer> element should contain information about its containing element.
A <footer> element typically contains:
authorship information
copyright information
contact information
sitemap
back to top links
related documents
You can have several <footer> elements in one document.
BODY
The <body> tag defines the document's body. The <body> element contains all the contents of an HTML document, such as text, hyperlinks, images, tables, lists, etc.