Example
Headings can be used to describe the topic they precede and they are defined with the <h1> to <h6> tags. Headings support all the global attributes.
<h1>defines the most important heading.<h6>defines the least important heading.
Defining a heading:
<h1>Heading 1</h1>
<h2>Heading 2</h2>
<h3>Heading 3</h3>
<h4>Heading 4</h4>
<h5>Heading 5</h5>
<h6>Heading 6</h6>
Correct structure matters
Search engines and other user agents usually index page content based on heading elements, for example to create a table of contents, so using the correct structure for headings is important.
In general, an article should have one h1 element for the main title followed by h2 subtitles – going down a layer if necessary. If there are h1 elements on a higher level they shoudn't be used to describe any lower level content.
Example document (extra intendation to illustrate hierarchy):
<h1>Main title</h1>
<p>Introduction</p>
<h2>Reasons</h2>
<h3>Reason 1</h3>
<p>Paragraph</p>
<h3>Reason 2</h3>
<p>Paragraph</p>
<h2>In conclusion</h2>
<p>Paragraph</p>
