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HTML: <!DOCTYPE> tag

This HTML tutorial explains how to use the HTML element called the <!DOCTYPE> tag with syntax and examples.

Description

The HTML <!DOCTYPE> tag is the very first line in the HTML document. It tells the browser what version of HTML the document is written so that the browser knows what to expect. This tag is also commonly referred to as the <!DOCTYPE> element.

Syntax

The syntax for the <!DOCTYPE> tag varies between on the version of HTML or XHTML you are using. Let's look at the most common usages.

The syntax in HTML5 is:

<!doctype html>

The syntax in HTML 4.01 Transitional is:

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

The syntax in XHTML 1.0 Transitional is:

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

The syntax in XHTML 1.0 Strict is:

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

The syntax in XHTML 1.1 is:

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

Browser Compatibility

The <!DOCTYPE> tag has basic support with the following browsers:

  • Chrome
  • Android
  • Firefox (Gecko)
  • Firefox Mobile (Gecko)
  • Internet Explorer (IE)
  • Edge Mobile
  • Opera
  • Opera Mobile
  • Safari (WebKit)
  • Safari Mobile

Example

We will discuss the <html> tag below, exploring examples of how to use the <html> tag in HTML5, HTML 4.01 Transitional, XHTML 1.0 Transitional, XHTML 1.0 Strict, and XHTML 1.1.