XHTML (eXtensible HyperText Markup Language)

What is XHTML?

XHTML, or eXtensible HyperText Markup Language, is a reformulation of HTML (HyperText Markup Language) that adheres to the stricter guidelines of XML (eXtensible Markup Language). It was introduced by the World Wide Web Consortium (W3C) as a way to combine the flexibility of HTML with the rigorous syntax rules of XML.

The main purpose of XHTML is to create a more structured and cleaner version of HTML that different devices and applications can easily process. This allows for better interoperability and compatibility across various platforms. Some key features of XHTML include:

  • Well-formed syntax: All elements in XHTML must be properly nested, closed, and have lowercase tags.
  • Strict nesting rules: Elements must be opened and closed correctly.
  • Attribute values must be quoted: All attribute values must be enclosed in quotes, single or double.
  • Mandatory declaration of namespaces: The XHTML namespace must be declared in the document’s root element.

Although XHTML was widely used in the past, it has been largely replaced by HTML5, which offers similar benefits in structure and interoperability while being more flexible and easier to work with.