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:
  • XHTML follows the syntax rules of XML, which means it must adhere to strict rules for element nesting, attribute quoting, and case sensitivity.
  • XHTML documents are well-formed XML documents, allowing them to be parsed and processed using standard XML tools and libraries.
• HTML Compatibility:
  • XHTML is designed to be compatible with HTML, allowing authors to write XHTML documents that are also valid HTML documents.
  • XHTML documents can be displayed and rendered by web browsers that support HTML, making it easy to transition existing HTML content to XHTML.
• Extensibility:
  • XHTML 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.
  • XHTML follows the same basic syntax and structure as HTML but is stricter and more well-formed, conforming to the rules of XML.
  • XHTML 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:
  • XHTML 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:
  • XHTML 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:
  • XHTML 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

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