HTML Doctype declaration
This is good practice for HTML documents that start with a <!DOCTYPE> declaration. The HTML <!DOCTYPE> is used to define which version of HTML the document is using .The DTD stand for document type declaration
<!DOCTYPE> tag is an information to the browser about what document type to expect.
Suggestion − The <!DOCTYPE> is an empty tag that does not have an end tag!.
Example for HTML Doctype declaration
<!DOCTYPE html>
<html>
<head>
<title>This is Doctype example</title>
</head>
<body>
All web page content.
</body>
</html>
In HTML5 there is only one declaration i.e.
<!DOCTYPE html>
Browser Support
Chrome | Firefox | IE | Opera | Safari | Android |
Yes | Yes | Yes | Yes | Yes | Yes |