Besides the somewhat obvious need they fill (people sometimes want to put headlines on top of things), the headline tags also have SEO value, help you to be a more organized writer, and make pages more user-friendly. ”  W3C

The

element defines a section in a document.. The HTML

elements represent six levels of section headings.

is the highest section level and

is the lowest. Headline Tags and SEO Although the order and occurrence of headings is not constrained by the HTML DTD, documents should not skip levels (for example, from H1 to H3), as converting such documents to other representations is often problematic. The source for this interactive example is stored in a GitHub repository. QUOTE :   “ The six heading elements, H1 through H6, denote section headings. Here is a brief explanation of each sectioning element and how they are used: