<P> HTML 4 defined three different versions of the language: Strict, Transitional (once called Loose) and Frameset . The Strict version is intended for new documents and is considered best practice, while the Transitional and Frameset versions were developed to make it easier to transition documents that conformed to older HTML specification or didn't conform to any specification to a version of HTML 4 . The Transitional and Frameset versions allow for presentational markup, which is omitted in the Strict version . Instead, cascading style sheets are encouraged to improve the presentation of HTML documents . Because XHTML 1 only defines an XML syntax for the language defined by HTML 4, the same differences apply to XHTML 1 as well . </P> <P> The Transitional version allows the following parts of the vocabulary, which are not included in the Strict version: </P> <Ul> <Li> A looser content model <Ul> <Li> Inline elements and plain text are allowed directly in: body, blockquote, form, noscript and noframes </Li> </Ul> </Li> <Li> Presentation related elements <Ul> <Li> underline (u) (Deprecated . can confuse a visitor with a hyperlink .) </Li> <Li> strike - through (s) </Li> <Li> center (Deprecated . use CSS instead .) </Li> <Li> font (Deprecated . use CSS instead .) </Li> <Li> basefont (Deprecated . use CSS instead .) </Li> </Ul> </Li> <Li> Presentation related attributes <Ul> <Li> background (Deprecated . use CSS instead .) and bgcolor (Deprecated . use CSS instead .) attributes for body (required element according to the W3C .) element . </Li> <Li> align (Deprecated . use CSS instead .) attribute on div, form, paragraph (p) and heading (h1...h6) elements </Li> <Li> align (Deprecated . use CSS instead .), noshade (Deprecated . use CSS instead .), size (Deprecated . use CSS instead .) and width (Deprecated . use CSS instead .) attributes on hr element </Li> <Li> align (Deprecated . use CSS instead .), border, vspace and hspace attributes on img and object (caution: the object element is only supported in Internet Explorer (from the major browsers)) elements </Li> <Li> align (Deprecated . use CSS instead .) attribute on legend and caption elements </Li> <Li> align (Deprecated . use CSS instead .) and bgcolor (Deprecated . use CSS instead .) on table element </Li> <Li> nowrap (Obsolete), bgcolor (Deprecated . use CSS instead .), width, height on td and th elements </Li> <Li> bgcolor (Deprecated . use CSS instead .) attribute on tr element </Li> <Li> clear (Obsolete) attribute on br element </Li> <Li> compact attribute on dl, dir and menu elements </Li> <Li> type (Deprecated . use CSS instead .), compact (Deprecated . use CSS instead .) and start (Deprecated . use CSS instead .) attributes on ol and ul elements </Li> <Li> type and value attributes on li element </Li> <Li> width attribute on pre element </Li> </Ul> </Li> <Li> Additional elements in Transitional specification <Ul> <Li> menu (Deprecated . use CSS instead .) list (no substitute, though unordered list is recommended) </Li> <Li> dir (Deprecated . use CSS instead .) list (no substitute, though unordered list is recommended) </Li> <Li> isindex (Deprecated .) (element requires server - side support and is typically added to documents server - side, form and input elements can be used as a substitute) </Li> <Li> applet (Deprecated . use the object element instead .) </Li> </Ul> </Li> <Li> The language (Obsolete) attribute on script element (redundant with the type attribute). </Li> <Li> Frame related entities <Ul> <Li> iframe </Li> <Li> noframes </Li> <Li> target (Deprecated in the map, link and form elements .) attribute on a, client - side image - map (map), link, form and base elements </Li> </Ul> </Li> </Ul> <Li> A looser content model <Ul> <Li> Inline elements and plain text are allowed directly in: body, blockquote, form, noscript and noframes </Li> </Ul> </Li>

Http is the markup language used to specify the contents of a web page