XHTML

XHTML stands for Extensible HyperText Markup Language and is an XML compliant variant of HTML. The language enforces strict syntax rules, all tags must be lowercase and closed, attributes must be in quotes. In the early 2000s XHTML was an attempt to push the web into a strictly structured form.

Historical background

The W3C developed XHTML as the successor to HTML 4. The idea was that strict structures would simplify machine processing and allow reliable content handling. With the failure of XHTML 2.0 and the rise of HTML5, XHTML lost importance, although many concepts flowed into HTML5.

Current relevance

In classic websites XHTML barely plays a role any more, HTML5 has established itself as the standard. In specialised areas such as email templates or structured documents the strict syntax remains useful because it guarantees a predictable DOM structure. XML based workflows like EPUB also use XHTML as the content format.

Context in marketing work

When creating email templates or newsletters you benefit from XHTML style notation because many mail clients tolerate HTML errors much worse than browsers. Consistently closed tags, clean attributes, and clear nesting significantly reduce rendering issues. When delivering technical specifications or document like content, sticking close to XHTML stays on the safe side.