Title tags in HTML, also known as heading tags, are used to add headings and subheadings to your HTML document. They are a great way to structure your content, making it easier for both users and search engines to read and understand.

The tag names range from h1 to h6, where h1 represents the highest level heading and h6 the lowest level heading.

Here is a basic example of how to use title tags:

```

Heading 1 – usually used for the main page title

Heading 2 – usually used for the main points on your page

Heading 3 – usually used for sub-points of your main points

Heading 4 – these are less common and typically used for smaller sub-points

Heading 5 – these are also less common, and smaller than h4 headers

Heading 6 – these are the smallest headers, and aren’t very commonly used

```

You can also style your headings with CSS:

```

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This sets h1 headers to red, h2 headers to blue, and h3 headers to green.

Remember to use these tags to structure your content logically for the best readability, and only use one h1 heading per page for SEO best practices.