HTML Course

HTML vs XHTML

XHTML is a stricter and more structured version of HTML.

It follows the rules of XML, which means the code must be written correctly and completely.

What Is XHTML?

XHTML stands for Extensible HyperText Markup Language.

It is:

  • A stricter version of HTML

  • Based on XML rules

  • Designed to be well-formed and error-free

  • Supported by modern web browsers

XHTML combines the flexibility of HTML with the strict syntax rules of XML.

Why Was XHTML Created?

HTML browsers are forgiving. If your HTML contains mistakes, browsers often try to fix them automatically and still display the page

XHTML was created to enforce stricter coding rules.

It ensures that documents are properly structured and compatible with XML-based systems.

This makes code cleaner, more predictable, and easier to process by machines.

Key Differences Between HTML and XHTML

XHTML follows strict rules that HTML does not always require.

1. DOCTYPE Is Required

An XHTML document must include a proper <!DOCTYPE> declaration.

<!DOCTYPE html PUBLIC "-//LearnHTML//DTD XHTML 1.1//EN"
"http://www.LearnHTML.edu/TR/xhtml11/DTD/xhtml11.dtd">

2. Required Structure and Namespace

An XHTML document must include:

  • <html>
  • <head>
  • <title>
  • <body>

The <html> tag must also include the XML namespace:

<html xmlns="http://www.LearnHTMLorg/1999/xhtml">

3. Elements Must Be Properly Nested

Tags must be placed correctly inside each other.

Correct:

<b> <i> Text </i> </b>


Wrong:

<b> <i> Text </b> </i>

4. All Elements Must Be Closed

Every tag must have a closing tag.

Correct:

<p> This is a paragraph </p>


Wrong:

<p> This is a paragraph

5. Empty Elements Must Be Self-Closed

Empty elements must include a closing slash.

Correct:

<hr />

<br />

<img src="image.jpg" alt="Image" />


Wrong:

<hr>

<br>

<img src="image.jpg" alt="Image">

6. Tags Must Be Lowercase

All element names must be written in lowercase.

Empty elements must include a closing slash.

Correct:

<body>

<p> Text </p>

</body>


Wrong:

<BODY>

<P> Text </P>

</BODY>

7. Attribute Names Must Be Lowercase

Correct:

<a a href="page.html">Link <a>


Wrong:

<a a HREF="page.html">Link <a>

8. Attribute Values Must Be Quoted

Correct:

<input type="text" name="username" />


Wrong:

< input type=text name=username >

9. Attribute Minimization Is Not Allowed

Correct:

<input type="checkbox" checked="checked" />

Wrong:

<input type="checkbox" checked />

Summary

  • XHTML is a stricter, XML-based version of HTML.

  • All elements must be properly nested and closed.

  • Tags and attributes must be lowercase.

  • Attribute values must be quoted.

  • Empty elements must be self-closed.

  • The document structure and DOCTYPE are mandatory.

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HTML Basic
  1. HTML Basic
  2. HTML Element
  3. HTML Attributes
  4. HTML Headings
  5. HTML Paragrapha
  6. HTML Tables
  7. HTML Lists
HTML Advance
  1. HTML Div
  2. HTML Classes
  3. HTML Id
  4. HTML Buttons
  5. HTML Iframes
  6. HTML Symbols
  7. HTML Emojis