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HTML 5 <!DOCTYPE> tag

Definition and Usage

The <!DOCTYPE> declaration is the very first thing in your document, before the <html> tag. This tag tells the browser which HTML specification the document uses.

Differences Between HTML 4.01 and HTML 5

While there is 3 different doctypes in HTML 4.01, there is only one in HTML 5:
<!DOCTYPE HTML>

Tips and Notes

Note: The <!DOCTYPE> tag does not have an end tag!

Tip: The <!DOCTYPE> declaration is NOT case sensitive.

HTML 5

In HTML5 the doctype declaration is simply:

<!DOCTYPE HTML>

It is important that you specify the doctype in all HTML documents, so that the browser knows what type of document to expect.

The doctype in HTML 4.01 required a reference to a DTD, because HTML 4.01 was based on SGML. HTML 5 is not based on SGML, and does not require a reference to a DTD, but need the doctype for browsers to behave as they should.

Attributes: NONE