!DOCTYPE

Summary

A Document Type Declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document (for example, a webpage) with a Document Type Definition (DTD) (for example, the formal definition of a particular version of HTML). In the serialized form of the document, it manifests as a short string of markup that conforms to a particular syntax. Not including <!DOCTYPE> may trigger Quirks mode.

Overview Table

DOM Interface: HTMLElement

Examples

HTML5 has one doctype declaration

<!DOCTYPE html>

HTML 4.01 Strict

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

HTML 4.01 Transitional

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

Usage

Add

<!DOCTYPE html>

to the start of your document.

Notes

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

This is not a HTML tag but an instruction for the browser about the version of the document.

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.

!DOCTYPE

Summary

Overview Table

Examples

Usage

Notes

See also

Related articles

Deprecated

HTML

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