Headings are defined with the <h1> to <h6> tags. <h1> defines the most important heading. <h6> defines the least important heading.
Search engines use the headings to index the structure and content of your web pages. It is important to use headings to show the document structure. <h1> headings should be used for main headings, followed by <h2> headings, then the less important <h3>, and so on.
HTML Headings Example