Editing HTML element (section)

===Element status===
Since the first version of HTML, several elements have become outmoded, and are ''[[deprecated]]'' in later standards, or do not appear at all, in which case they are ''invalid'' (and will be found invalid, and perhaps not displayed, by [[XML validation|validating]] user agents).<ref name="XML10-51">[[#XML10|XML 1.0]] §5.1</ref>

In [[HTML 4.01]] / [[XHTML 1.0]], the status of elements is complicated by the existence of three types of [[Document Type Definition|DTD]]:
* '''Transitional''', which contain deprecated elements, but which were intended to provide a transitional period during which authors could update their practices;
* '''Frameset''', which are versions of the Transitional DTDs which also allow authors to write '''frameset''' documents;
* '''Strict''', which is the up-to-date (as at 1999) form of HTML.

HTML5 instead provides a listing of '''obsolete''' features to go along with the '''standardized''' normative content. They are broken down into "obsolete but conforming" for which implementation instructions exist and "non-conforming" ones that should be replaced.<ref>[[#WHATWGLS|WHATWGLS]]. § 15</ref>

The first Standard ([[HTML#HTML 2|HTML 2.0]]) contained four deprecated elements, one of which was invalid in [[HTML 3.2]]. All four are invalid in [[HTML 4|HTML 4.01 Transitional]], which also deprecated a further ten elements. All of these, plus two others, are invalid in [[HTML 4|HTML 4.01 Strict]]. While the frame elements are still current in the sense of being present in the Transitional and Frameset DTDs, there are no plans to preserve them in future standards, as their function has been largely replaced, and they are highly problematic for user accessibility.

(Strictly speaking, the most recent ''XHTML'' standard, [[XHTML 1.1]] (2001), does not include frames at all; it is approximately equivalent to [[XHTML 1.0|XHTML 1.0 Strict]], but also includes the '''[[Ruby (annotation markup)|Ruby markup]]''' module.)<ref name="XHTML11">[[#XHTML11|XHTML 1.1]] §A</ref>

A common source of confusion is the loose use of ''deprecated'' to refer to both deprecated and invalid status, and to elements that are expected to be formally deprecated in the future.