What is Header/ Heading Tags?
Heading tags (<h1> through <h6>) organize the HTML elements of a web page by marking the head and subhead of the page. Search engine algorithms use these marks to identify the relevance and hierarchy of information within the page because plain text formatting does not convey meaning. Following proper heading hierarchy practice—saving <h1> for the page title and using <h2>, <h3>, etc. for subdivisions—improves both usability and SEO.
As an example, a blog post can mark its headline with <h1>, use <h2> for section titles, and <h3> for subsections beneath those.
Related terms: title tag, subtitle, document outline, semantic HTML