Headings in HTML establish the hierarchy of information on a webpage. There are six levels of headings, from most important to least significant:
<h1>Heading 1</h1> <h2>Heading 2</h2> <h3>Heading 3</h3> <h4>Heading 4</h4> <h5>Heading 5</h5> <h6>Heading 6</h6>