HTML headings are defined with the <h1> to <h6> tags:

•  <h1>This is a heading</h1>
•  <h2>This is a heading</h2> 
• <h3>This is a heading</h3> 
• <h4>This is a heading</h4> 
• <h5>This is a heading</h5>
•  <h6>This is a heading</h6>

 Headings are important for accessibility and search engine optimization. 

• <h1> defines the most important heading. 
• <h6> defines the least important heading.

Output:-