HTML Header overview

Headers in HTML and XHTML are tags used to define the headings within your page. There are six levels of headings, from <h1> . . . </h1> to <h6> . . .</h6>. The <h1> . . . </h1> level header is considered the most significant header, such as a page title, with an <h2> . . .</h2> level header performing as a subhead and so on. Headers at the fifth and sixth levels are rarely used

Example

<h1>Hello world!</h1>
<h2>Hi</h2>
<h3>Hey</h3>
<h4>How are you</h4>