HTML Document Types Definitions

A (DTD) Doctype is used to declare the type of Html or Xhtml markup the Web author is supposedly using in the document. HTML 4.01 specifies Three Doctype Definitions. Each vary in the elements they support, so web authors must include one of the following document type declarations in their Html documents (Webpages).

HTML 4.0 Transitional DTD

HTML 4.0 Strict DTD

HTML 4.0 Framrset DTD

HTML 4.01 Transitional DTD

HTML 4.01 Strict DTD

HTML 4.01 Frameset DTD

XHTML 1.0 Basic DTD

XHTML 1.0 Strict DTD With Name Space

XHTML 1.0 Transitional DTD

XHTML 1.0 Frameset DTD

New HTML5 Doctype