HTML <!DOCTYPE> Declaration

The HTML element appears on the first line of the HTML page.

It informs the browser about the HTML version used in the document, so the browser knows what to anticipate.

This tag is also generally known as the element HTML.

Syntax

< !DOCTYPE html >

<!DOCTYPE html>
<html>
<body>

<h1>This is Doctype Tag</h1>

</body>
</html>

Element	Chrome	Firefox	Safari	Edge / IE	Opera
<!DOCTYPE>	Yes	Yes	Yes	Yes	Yes

<a>