XHTML, step by step

Get started working with Extensible Hypertext Markup Language. XHTML is a language based on HTML, but expressed in well-formed XML. However, XHTML has more to offer than just regularizing tags and characters -- XHTML can alter the way you approach Web design. This tutorial gives step-by-step instruction for developers familiar with HTML who want to learn how to use XHTML in practical Web sites.

Table of contents

• Introducing XHTML
• Who should take this tutorial?
• Prerequisites
• About the examples in this tutorial
• Anatomy of an XHTML Web page
• The flavors of XHTML
• The XML declaration
• Document type declarations
• Main elements and namespace
• A complete example
• Understand the ground rules
• Avoid obsolete elements
• Use an end tag for all elements
• Incorrect XHTML
• Correct XHTML
• Use proper form for all attributes
• Use the xml:lang attribute
• Replace common HTML idioms
• Use stylesheets to set font and text details
• Use the XML stylesheet processing instruction
• Use style to align content
• Align content with an internal stylesheet
• Use ins and del to express edited content
• Do not use text/html with XHTML 1.1
• Use the W3C XHTML validator
• Use the XML declaration for character encoding
• Use XSLT to provide standby conversion to HTML
• Embed XHTML in other vocabularies
• XSLT document with embedded XHTML

The context surrounding XHTML
A language is always born in a particular context and it is usually the expression of a need that has been felt at a given moment. XHTML is no exception, and I would even add that we can not understand the value of this markup language without knowing the stakes of its existence.

A markup language
Before going further, you must understand a simple but often forgotten notion, even by insiders. XHTML is a markup language.