The DOCTYPE declaration is an instruction found at the top of an HTML or XHTML document that tells the user agent what version of HTML the document uses.
The correct DOCTYPE for modern documents is the HTML5 DOCTYPE:
<!doctype html>
More Information About DOCTYPE
The DOCTYPE Element
Learn the rules in the HTML specification for using the DOCTYPE declaration.
Anatomy of a DOCTYPE
DOCTYPE declarations can have several different parts. Learn what all the different bits are and when you should and shouldn't use them.
List of DOCTYPEs and the Web Pages They Generate
This article covers what features are part of different DOCTYPEs and when you might choose to use one over another.
Quirks Mode and DOCTYPE Declarations
If you don't use a DOCTYPE your page will render in quirks mode. Here is some information about quirks mode and why you should be aware of it.
Quirks Mode
This article explains what quirks mode is, how you trigger it, and why you should avoid it.
Why Use DOCTYPE Declarations
This article goes into more detail about some of the strange things that can happen in quirks mode.
dahk taip — (noun)
There are several synonyms that mean the same thing as DOCTYPE:
DOCTYPEdeclarationDTD—Which is really a part of aDOCTYPE, and not a synonym at all.- Document Type Declaration
The best DOCTYPE to use now is the HTML5 DOCTYPE. And it's also very easy to remember:
<!doctype html>
Other DOCTYPE examples include:
HTML 4.01 Strict
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
XHTML 1.0 Transitional
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
