Headings are used to indicate page or section headers in a web document. HTML defines six headings: h1 to h6 where the highest font size heading is defined by h1 while the lowest font size heading is defined by h6.

<h1>This is heading 1</h1> 
<h2>This is heading 2</h> 
<h3>This is heading 3</h3> 

These will produce the following results:

This is heading 1

This is heading 2

This is heading 3