From http://www.w3schools.com (Copyright Refsnes Data)

HTML Headings

Headings are important in HTML documents.

HTML Headings

Headings are defined with the <h1> to <h6> tags.

<h1> defines the largest heading. <h6> defines the smallest heading.

<h1>This is a heading</h1>
<h2>This is a heading</h2>
<h3>This is a heading</h3>

Try it yourself

Note: Browsers automatically adds an empty line before and after headings.

Headings Are Important

Use the HTML heading tags for headings only. Don't use headings to make something BIG or bold.

Search engines use your headings to index the structure and content of your web pages.

Since users may skim your pages by its headings, it is important to use headings to show the document structure.

H1 headings should be used as main headings, followed by H2 headings, and less important H3 headings, and so on.

HTML Comments

Comments can be inserted in the HTML code to make it more readable and understandable. Comments are ignored by the browser and not displayed.

Comments are written like this:

<!-- This is a comment -->

Try it yourself

Note: There is an exclamation point after the opening bracket, but not before the closing bracket.

HTML Tip - How to View HTML Source

Have you ever seen a Web page and wondered "Hey! How did they do that?"

To find out, click the VIEW option in your browser's toolbar and select SOURCE or PAGE SOURCE. This will open a window that shows you the HTML code of the page.

Examples From This Page

Headings
This example demonstrates the tags that display headings in an HTML document.

Hidden comments
This example demonstrates how to insert a hidden comment in the HTML source code.

HTML Tag Reference

When you lookup W3Schools' tag reference, you will see additional information about tags and their attributes.

You will learn more about HTML tag attributes in the next chapters of this tutorial.

From http://www.w3schools.com (Copyright Refsnes Data)