HTML Doctypes

All HTML documents must start with a `<!DOCTYPE>` declaration.

HTML DOCTYPE Declaration

All HTML documents must start with a <!DOCTYPE> declaration.

The doctype declaration is not an HTML tag. It is an "instruction" to the browser about what document type to expect.

The doctype declaration appears at the beginning of an HTML document, before the <html> tag.

In HTML5, the <!DOCTYPE> declaration is simple:

Example Code

html

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<!DOCTYPE html>

Note: The <!DOCTYPE> declaration is not case-sensitive.

Other DOCTYPE Declarations

In older documents (HTML 4 or XHTML), the declaration is more complicated because the declaration must refer to a DTD (Document Type Definition).

HTML 4.01:

Example Code

html

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

XHTML 1.1:

Example Code

html

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

Valid HTML Elements in Different DOCTYPES

Tag	HTML 5	HTML 4	XHTML
`<a>`	Yes	Yes	Yes
`<abbr>`	Yes	Yes	Yes
`<acronym>`	No	Yes	Yes
`<address>`	Yes	Yes	Yes
`<applet>`	No	Yes	No
`<area>`	Yes	Yes	No
`<article>`	Yes	No	No
`<aside>`	Yes	No	No
`<audio>`	Yes	No	No
`<b>`	Yes	Yes	Yes
`<base>`	Yes	Yes	Yes
`<basefont>`	No	Yes	No
`<bdi>`	Yes	No	No
`<bdo>`	Yes	Yes	No
`<big>`	No	Yes	Yes
`<blockquote>`	Yes	Yes	Yes
`<body>`	Yes	Yes	Yes
`<br>`	Yes	Yes	Yes
`<button>`	Yes	Yes	Yes
`<canvas>`	Yes	No	No
`<caption>`	Yes	Yes	Yes
`<center>`	No	Yes	No
`<cite>`	Yes	Yes	Yes
`<code>`	Yes	Yes	Yes
`<col>`	Yes	Yes	No
`<colgroup>`	Yes	Yes	No
`<data>`	Yes	No	No
`<datalist>`	Yes	No	No
`<dd>`	Yes	Yes	Yes
`<del>`	Yes	Yes	No
`<details>`	Yes	No	No
`<dfn>`	Yes	Yes	Yes
`<dialog>`	Yes	No	No
`<dir>`	No	Yes	No
`<div>`	Yes	Yes	Yes
`<dl>`	Yes	Yes	Yes
`<dt>`	Yes	Yes	Yes
`<em>`	Yes	Yes	Yes
`<embed>`	Yes	No	No
`<fieldset>`	Yes	Yes	Yes
`<figcaption>`	Yes	No	No
`<figure>`	Yes	No	No
`<font>`	No	Yes	No
`<footer>`	Yes	No	No
`<form>`	Yes	Yes	Yes
`<frame>`	No	Yes	No
`<frameset>`	No	Yes	No
<h1> to <h6>	Yes	Yes	Yes
`<head>`	Yes	Yes	Yes
`<header>`	Yes	No	No
`<hr>`	Yes	Yes	Yes
`<html>`	Yes	Yes	Yes
`<i>`	Yes	Yes	Yes
`<iframe>`	Yes	Yes	No
`<img>`	Yes	Yes	Yes
`<input>`	Yes	Yes	Yes
`<ins>`	Yes	Yes	No
`<kbd>`	Yes	Yes	Yes
`<label>`	Yes	Yes	Yes
`<legend>`	Yes	Yes	Yes
`<li>`	Yes	Yes	Yes
`<link>`	Yes	Yes	Yes
`<main>`	Yes	No	No
`<map>`	Yes	Yes	No
`<mark>`	Yes	No	No
`<meta>`	Yes	Yes	Yes
`<meter>`	Yes	No	No
`<nav>`	Yes	No	No
`<noframes>`	No	Yes	No
`<noscript>`	Yes	Yes	Yes
`<object>`	Yes	Yes	Yes
`<ol>`	Yes	Yes	Yes
`<optgroup>`	Yes	Yes	Yes
`<option>`	Yes	Yes	Yes
`<output>`	Yes	No	No
`<p>`	Yes	Yes	Yes
`<param>`	Yes	Yes	Yes
`<picture>`	Yes	No	No
`<pre>`	Yes	Yes	Yes
`<progress>`	Yes	No	No
`<q>`	Yes	Yes	Yes
`<rp>`	Yes	No	No
`<rt>`	Yes	No	No
`<ruby>`	Yes	No	No
`<s>`	Yes	Yes	No
`<samp>`	Yes	Yes	Yes
`<script>`	Yes	Yes	Yes
`<section>`	Yes	No	No
`<select>`	Yes	Yes	Yes
`<small>`	Yes	Yes	Yes
`<source>`	Yes	No	No
`<span>`	Yes	Yes	Yes
`<strike>`	No	Yes	No
`<strong>`	Yes	Yes	Yes
`<style>`	Yes	Yes	Yes
`<sub>`	Yes	Yes	Yes
`<summary>`	Yes	No	No
`<sup>`	Yes	Yes	Yes
`<table>`	Yes	Yes	Yes
`<tbody>`	Yes	Yes	No
`<td>`	Yes	Yes	Yes
`<template>`	Yes	No	No
`<textarea>`	Yes	Yes	Yes
`<tfoot>`	Yes	Yes	No
`<th>`	Yes	Yes	Yes
`<thead>`	Yes	Yes	No
`<time>`	Yes	No	No
`<title>`	Yes	Yes	Yes
`<tr>`	Yes	Yes	Yes
`<track>`	Yes	No	No
`<tt>`	No	Yes	Yes
`<u>`	Yes	Yes	No
`<ul>`	Yes	Yes	Yes
`<var>`	Yes	Yes	Yes
`<video>`	Yes	No	No
`<wbr>`	Yes	No	No

Interactive Code Examples

Example 1

html

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Runnable HTML example from EA Academy.

<!DOCTYPE html>

Example 2

html

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Runnable HTML example from EA Academy.

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

Example 3

html

Try it Yourself

Runnable HTML example from EA Academy.

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

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