HTML <html> xmlns Attribute

Example

A simple XHTML document, with the minimum of required tags:

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

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Title of the document</title>
</head>

<body>
The content of the document......
</body>

</html>

Try it Yourself »

Definition and Usage

The xmlns attribute specifies the xml namespace for a document.

Note: The xmlns attribute is required in XHTML, invalid in HTML 4.01, and optional in HTML5.

Note: The HTML validator at http://w3.org does not complain when the xmlns attribute is missing in an XHTML document. This is because the namespace "xmlns=http://www.w3.org/1999/xhtml" is default, and will be added to the <html> tag even if you do not include it.