XHTML

Introduction

• XHTML stands for ‘Extensible Hypertext Markup Language’.
• While XHTML has been largely replaced by HTML5 in recent years, it remains an important part of web development history and continues to be used in certain contexts.

Definition

• XHTML is a markup language that combines the extensibility of XML(with the syntax and rules of XML) with the familiarity of HTML, providing a versatile and standardized markup language for creating web pages and applications.
• XHTML combines the familiar syntax of HTML with the strictness and extensibility syntax of XML, providing a standardized and interoperable markup language for creating web documents that are well-formed, accessible, and compatible with modern web standards.

Characteristics

• XML-Based Syntax:
  • It follows the syntax rules of XML, which means it must adhere to strict rules for element nesting, attribute quoting, and case sensitivity.
  • It documents are well-formed XML documents, allowing them to be parsed and processed using standard XML tools and libraries.
• HTML Compatibility:
  • It is designed to be compatible with HTML, allowing authors to write XHTML documents that are also valid HTML documents.
  • It documents can be displayed and rendered by web browsers that support HTML, making it easy to transition existing HTML content to XHTML.
• Extensibility:
  • It is extensible, allowing authors to define custom elements, attributes, and document structures using XML namespaces. This enables the creation of specialized markup languages and vocabularies tailored to specific applications or industries.
  • It follows the same basic syntax and structure as HTML but is stricter and more well-formed, conforming to the rules of XML.
  • It was designed to provide the compatibility and extensibility of XML while maintaining the simplicity and familiarity of HTML.
• Document Structure:
  • Like HTML, XHTML documents consist of elements that define the structure and content of a web page.
  • Elements are marked up using tags enclosed in angle brackets (<>) and can contain attributes to provide additional information or behavior.
• Strictness and Error Handling:
  • It is more strict than HTML in terms of syntax and error handling.
  • It requires proper nesting of elements, quoting of attribute values, and adherence to XML rules.
  • Browsers may handle XHTML documents differently depending on their level of XML support and the presence of errors.
• Versions:
  • It has several versions, including XHTML 1.0, XHTML 1.1, and XHTML 5.
  • Each XHTML version may have different features, requirements, and compatibility considerations.
• Accessibility and Semantic Markup:
  • It encourages the use of semantic markup to enhance accessibility and search engine optimization (SEO).
  • Semantic markup involves using HTML elements to convey the meaning and structure of content, making it easier for assistive technologies and search engines to understand and interpret web pages.

Use/Applications

• It is commonly used in web development for creating structured, well-formed web pages and documents.
• It is often used in conjunction with CSS (Cascading Style Sheets) for styling and JavaScript for interactivity to create dynamic and responsive web applications.