What is XHTML?

Markup is the heart of any Web page. It gives content structure and meaning. In order to represent it, the W3C has defined two very similar standards: HTML and XHTML. The former is based on the legendary (and very permissible) SGML language. The latter, while very similar, has a different ancestor: XML. This implies that valid XHTML pages can be processed as any other XML documents, which makes it suitable for mobile devices and others with low processing power. Both standards are equally powerful, but XHTML has the added benefit of speaking the lingua franca of the internet. Developers learn how to deal with XML documents since their very first programming lessons. Hundreds of XML manipulation libraries exist for every possible programming language. Thus, being able to feed Web pages into this existing machinery is surely an added value.

See Also

• What are web standards?

• HTML 4.01 specification