HTML/Usage/Headings

From W3C Wiki

Use h1 to h6 to identify document structure

Using only h1 elements in a HTML document results in a flat document outline as heading element semantics are conveyed to users as per the numeric in the heading element tag name.

Include a heading to identify article and section elements

As a general rule, include a heading (h1-h6) as a child of each section and article element.