In HTML5, you can just use the following Doctype before the <html> tag.
<!DOCTYPE html>
Quote from W3Schools
The declaration must be the very first thing in your HTML5 document, before the tag.
The declaration is not an HTML tag; it is an instruction to the web browser about what version of HTML the page is written in.
In HTML 4.01, all declarations require a reference to a DTD, because HTML 4.01 was based on SGML.
HTML5 is not based on SGML, and therefore does not require a reference to a DTD.
To start a HTML5 page, you can use the following template.
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
</head>
<body></body>
</html>
Done =)
Reference:
Eureka! 