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Topics

HTML Basics

Introduction to HTMLHTML Document StructureHTML ElementsHTML AttributesHTML HeadingsHTML ParagraphsHTML Text FormattingHTML CommentsHTML LinksHTML ImagesHTML ListsHTML TablesHTML Blocks and Inline ElementsHTML ClassesHTML IdHTML IframesHTML File PathsHTML HeadHTML Layout ElementsHTML Responsive Web Design

HTML Forms and Input

HTML FormsHTML Form AttributesHTML Form ElementsHTML Input TypesHTML Input AttributesHTML Input Form AttributesHTML TextareaHTML ButtonsHTML SelectHTML DatalistHTML OutputHTML Form Example

HTML5 Features

HTML5 IntroductionHTML5 New ElementsHTML5 Semantic ElementsHTML5 FormsHTML5 GraphicsHTML5 MediaHTML5 APIsHTML5 GeolocationHTML5 Drag and DropHTML5 Web StorageHTML5 Web WorkersHTML5 Server-Sent EventsHTML5 CanvasHTML5 SVGHTML5 AudioHTML5 Video

HTML Advanced Topics

HTML EntitiesHTML SymbolsHTML EmojisHTML CharsetHTML URL EncodeHTML XHTMLHTML Style GuideHTML vs. XHTMLHTML AccessibilityHTML Best PracticesHTML SEO BasicsHTML MetadataHTML Responsive ImagesHTML Picture ElementHTML FaviconHTML Performance Optimization

HTML and Other Technologies

HTML and CSSHTML and JavaScriptHTML DOMHTML EventsHTML Web ComponentsHTML TemplatesHTML Custom ElementsHTML Shadow DOMHTML MicrodataHTML and XMLHTML and JSONHTML and ARIAHTML and SVGHTML and MathML

HTML Tools and Resources

HTML EditorsHTML ValidatorsHTML Color CodesHTML Character CodesHTML Language CodesHTML Country CodesHTML DoctypesHTML Canvas ReferenceHTML Audio/Video DOM ReferenceHTML Attribute ReferenceHTML Event ReferenceHTML Color NamesHTML Web Storage Objects

HTML and XHTML: Understanding the Differences

HTML (Hypertext Markup Language) and XHTML (Extensible Hypertext Markup Language) are both markup languages used for creating web pages. While they share many similarities, there are key differences in their syntax and rules.

What is XHTML?

XHTML is a stricter, more XML-based version of HTML. It was developed to make HTML more extensible and increase the interoperability with other data formats. The main goal of XHTML is to create well-structured, standards-compliant web documents.

Key Differences Between HTML and XHTML

  • Document Structure: XHTML requires a proper document structure, including the DOCTYPE declaration and namespace.
  • Element Writing: All elements in XHTML must be properly nested and closed.
  • Attribute Values: In XHTML, all attribute values must be quoted.
  • Case Sensitivity: XHTML is case-sensitive for elements and attributes, typically using lowercase.

XHTML Syntax Examples

Here's an example of a simple XHTML document:


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
    <title>XHTML Example</title>
</head>
<body>
    <h1>Welcome to XHTML</h1>
    <p>This is a paragraph in XHTML.</p>
    <br />
    <img src="image.jpg" alt="An example image" />
</body>
</html>

Best Practices for XHTML

  1. Always include the proper DOCTYPE declaration.
  2. Close all elements, including empty ones (e.g., <br />).
  3. Use lowercase for all element and attribute names.
  4. Quote all attribute values.
  5. Properly nest all elements.

HTML5 and the Future

With the advent of HTML5, the strict rules of XHTML have become less prevalent. HTML5 allows for more flexibility while still encouraging good coding practices. However, understanding XHTML principles can help in writing cleaner, more structured HTML code.

Conclusion

While XHTML is less commonly used today, its principles of well-structured, standards-compliant markup remain valuable. Whether you're using HTML5 or XHTML, focusing on clean, semantic code will result in more maintainable and accessible web documents.

For more information on modern HTML practices, check out our guide on HTML Best Practices.