Extensible Hypertext Markup Language (XHTML)

Definition - What does Extensible Hypertext Markup Language (XHTML) mean?

Extensible hypertext markup language (XHTML) is a hybrid language between XML and HTML and is also an accepted standard in the coding world.

It is similar to HTML 4.01 and is considered as HTML defined as an application of XML. Unlike HTML, XHTML pages have a strict syntax and needs to be well formed in order to be parsed using XML parsers, unlike the more lenient HTML specific parsers.

Techopedia explains Extensible Hypertext Markup Language (XHTML)

Features of XHTML:

Unlike HTML, which is standard generalized markup language based, XHTML is XML-based.
Compared to the rules of HTML, XHTML is stricter and does not allow any lapses in coding or structure. It prohibits the omission of any tags or usage of attribute minimization. All elements in XHTML must have a starting or ending tag.
It is a restrictive subset of XML and needs to be parsed with help of standard XML parsers.
XHTML documents has only one root element.
As they are XML conforming, XHTML documents are easily viewed edited using standard XML tools.
Unlike HTML, XHTML provides a more cleaner, consistent and well-structured format which helps in making the webpages easily parseable for present and future browsers.
Sustainability is more pronounced in case of XHTML than HTML.
As the error processing routines are shorter, future browsers can support faster processing of XHTML documents.
As XHTML can support wide range of applications, using the same complex websites can be created.
XHTML elements needs to be nester properly and should always be in lower case.