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HTML <!DOCTYPE> declaration

The <!DOCTYPE> declaration is used for specifying which version of HTML the document is using.

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

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Browser compatibility

The <!DOCTYPE> declaration is fully supported by all browsers:

<!DOCTYPE> yes yes yes yes yes

Common Document type declarations (DTDs)

There are three different <!DOCTYPE> declarations in HTML 4.01 − HTML 4 Strict, HTML 4 Transitional, and HTML 4 Frameset.

In HTML5 there is only one declaration.

HTML 4 Strict

This document type includes all HTML elements except those that have been deprecated, and those that appear in frameset documents:

HTML 4 Transitional

This document type includes all HTML elements including those that have been deprecated:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "">
HTML 4 Frameset

This document type includes all HTML elements in the transitional DTD as well as those in framed document:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "">

In HTML5 there is only one declaration:

<!DOCTYPE html>

All HTML5 documents must start with a <!DOCTYPE html>
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Last updated: Monday 17 Sep, 2018