There are six different HTML headings Tag. The <h1> to <h6> tags are used to define headings mean title or a subtitle of HTML web pages. <h1> defines the main heading while <h6> defines the least important heading of a website.
When you put the text within the heading tags <h1>......</h1>, it gets visible on the browser in the bold format and size of the text depends on the number of headings.
h1 is the most important heading, which is used to display the main title of the page.
<h1>This is heading 1. This is main heading of page.</h1>
<p>h1 is the most important heading, which is used to display the keyword of page</p>
<h2>This is heading 2</h2>
<h3>This is heading 3</h3>
<h4>This is heading 4</h4>
<h5>This is heading 5</h5>
<h6>This is heading 6</h6>