HTML Declaration

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HTML <!DOCTYPE> Declaration

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Example

<!DOCTYPE html>

<html>

<head>

<title>Title of the document</title>

</head>

<body>

The content of the document......

</body>

</html>

Try it Yourself »

Definition and Usage

The <!DOCTYPE> declaration must be the very first thing in your HTML
document, before the <html> tag.

The <!DOCTYPE> 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, the <!DOCTYPE> declaration refers to a DTD, because HTML 4.01
was based on SGML. The DTD specifies the rules for the markup language, so that
the browsers render the content correctly.

HTML5 is not based on SGML, and therefore does not require a reference to a
DTD.

Tip: Always add the <!DOCTYPE> declaration to your HTML documents, so
that the browser knows what type of document to expect.

Browser Support

Element
<!DOCTYPE>	Yes	Yes	Yes	Yes	Yes

Differences Between HTML 4.01 and HTML5

There are three different <!DOCTYPE> declarations in HTML 4.01. In HTML5 there is only one:

<!DOCTYPE html>

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HTML Elements and Doctypes

Look at our table of all HTML elements, and what Doctype each element appears in.

Tips and Notes

Tip: The <!DOCTYPE> declaration is NOT case sensitive.

Tip: To check if the HTML of your Web documents is valid, go to W3C's validation service.

Common DOCTYPE Declarations

HTML 5

<!DOCTYPE html>

HTML 4.01 Strict

This DTD contains all HTML elements and attributes, but does NOT INCLUDE presentational or deprecated elements (like font). Framesets are not allowed.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">

HTML 4.01 Transitional

This DTD contains all HTML elements and attributes, INCLUDING presentational and deprecated elements (like font). Framesets are not allowed.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

HTML 4.01 Frameset

This DTD is equal to HTML 4.01 Transitional, but allows the use of frameset content.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">

XHTML 1.0 Strict

This DTD contains all HTML elements and attributes, but does NOT INCLUDE presentational or deprecated elements (like font). Framesets are not allowed. The markup must also be written as well-formed XML.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

XHTML 1.0 Transitional

This DTD contains all HTML elements and attributes, INCLUDING presentational and deprecated elements (like font). Framesets are not allowed. The markup must also be written as well-formed XML.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

XHTML 1.0 Frameset

This DTD is equal to XHTML 1.0 Transitional, but allows the use of frameset content.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">

XHTML 1.1

This DTD is equal to XHTML 1.0 Strict, but allows you to add modules (for example to provide
Ruby support for East-Asian languages).

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">