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Remarks.

Remarks

The <!DOCTYPE> declaration is not an HTML tag. It is used for specifying which version of HTML the document is using. This is referred to as the document type declaration (DTD).

The <!DOCTYPE> declaration is NOT case sensitive. To check if the HTML of your Web pages is valid, go to W3C's validation service.

  • Some old versions of IE don't support some HTML tags unless a proper doctype is available.
  • It's vital that a doctype is declared as to make sure the browser doesn't use quirks mode. More info on MDN. :::