Heading tags give the user a clear idea of what the page content is about. Today's users of the web, skim pages by reading the different heading tags on a page. It is important to use headings to show the document structure and it's also important for a web page to have properly structure content for accessibility devices.
Example of a heading structure:
Heading 1 : <h1>
Should be used for main headings.
Heading 2 : <h2>
Used after <h1> to designate second most important content on a page.
Heading 3 : <h3>
Used after <h3> to designate third most important content on a page.
Heading 4 : <h4>
Used after <h3> to designate fourth most important content on a page.