HTML 5 Declaration

Definition and Usage

The declaration must be the very first thing in your HTML5 document, before the tag. This tag tells the browser which HTML specification the document uses.

The doctype declaration is not an HTML tag; it is an instruction to the web browser about what version of the markup language the page is written in.

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.

---

Differences Between HTML 4.01 and HTML 5

There are 3 different doctypes in HTML 4.01, In HTML 5 there is only one:

Tips and Notes

Note: The tag does not have an end tag.

Tip: The declaration is NOT case sensitive.