HTML <!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
or XHTML specification the document uses.
Tips and Notes
Note: The <!DOCTYPE> tag does not have an end tag!
HTML
HTML 4.01 specifies three document types: Strict, Transitional, and Frameset.
HTML Strict DTD
Use this when you want clean markup, free of presentational clutter. Use this
together with Cascading Style Sheets (CSS):
| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> |
HTML Transitional DTD
The Transitional DTD includes presentation attributes and elements that
W3C expects to move to a style sheet. Use this when you need to use HTML's
presentational features because your readers don't have browsers that support
Cascading Style Sheets (CSS):
| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
Frameset DTD
The Frameset DTD should be used for documents with frames. The Frameset DTD is
equal to the Transitional DTD except for the frameset element replaces the body
element:
| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd"> |
XHTML
XHTML 1.0 specifies three XML document types: Strict, Transitional, and Frameset.
XHTML Strict DTD
Use this DTD when you want clean markup, free of presentational clutter. Use
this together with Cascading Style Sheets (CSS):
|
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
|
XHTML Transitional DTD
Use this DTD when you need to use XHTML's presentational features because
your readers don't have browsers that support Cascading Style Sheets (CSS):
|
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
XHTML Frameset DTD
Use this DTD when you want to use frames!
|
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">
|
To check that you have written a valid XHTML document with a correct DTD,
you can link your XHTML page to an XHTML validator.
Attributes: NONE
| 
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