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HTML vs XHTML
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HTML vs XHTML
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<h1>HTML<span class="color_h1"> Versus XHTML</span></h1>
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<hr>
<p class="intro">XHTML is a stricter, more XML-based version of HTML.</p>
<hr>
<h2>What is XHTML?</h2>
<ul>
<li>XHTML stands for E<strong>X</strong>tensible <strong>H</strong>yper<strong>T</strong>ext
<strong>M</strong>arkup <strong>L</strong>anguage</li>
<li>XHTML is a stricter, more XML-based version of HTML</li>
<li>XHTML is HTML defined as an XML application</li>
<li>XHTML is supported by all major browsers</li>
</ul>
<hr>
<h2>Why XHTML?</h2>
<p>XML is a markup language where all documents must be marked up correctly (be "well-formed").</p>
<p>XHTML was developed to make HTML more extensible and flexible to work with
other data formats (such as XML). In addition, browsers ignore errors in HTML
pages, and try to display the website even if it has some errors in the markup.
So XHTML comes with a much stricter error handling.</p>
<p>If you want to study XML, please read our <a href="/xml/default.asp">XML Tutorial</a>.</p>
<hr>
<h2>The Most Important Differences from HTML</h2>
<ul>
<li><!DOCTYPE> is <strong>mandatory</strong></li>
<li>The xmlns attribute in <html> is <strong>mandatory</strong></li>
<li><html>, <head>, <title>, and <body> are <strong>mandatory</strong></li>
<li>Elements must always be <b> properly nested</b></li>
<li>Elements must always be <b>closed</b></li>
<li>Elements must always be in <b>lowercase</b></li>
<li>Attribute names must always be in <b>lowercase</b></li>
<li>Attribute values must always be <b>quoted</b></li>
<li>Attribute minimization is <b>forbidden</b></li>
</ul>
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<h2>XHTML - <!DOCTYPE ....> Is Mandatory</h2>
<p>An XHTML document must have an XHTML <!DOCTYPE> declaration.</p>
<p>The <html>, <head>, <title>, and <body> elements must also be present, and the xmlns attribute in <html>
must specify the xml namespace for the document.</p>
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<h3>Example</h3>
<p>Here is an XHTML document with a minimum of required tags: </p>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"<br>
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"><br><html xmlns="http://www.w3.org/1999/xhtml"><br>
<head><br>
<title>Title of document</title><br>
</head><br>
<body><br><br> <em>some content here...</em> <br>
<br></body><br>
</html></div>
</div>
<hr>
<h2>XHTML Elements Must be Properly Nested</h2>
<p>In XHTML, elements must always be properly nested within each other, like this:</p>
<div class="w3-example">
<h3>Correct:</h3>
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<b><i>Some
text</i></b></div></div>
<div class="w3-example">
<h3>Wrong:</h3>
<div class="w3-code notranslate htmlHigh">
<b><i>Some
text</b></i></div></div>
<hr>
<h2>XHTML Elements Must Always be Closed</h2>
<p>In XHTML, elements must always be closed, like this:</p>
<div class="w3-example">
<h3>Correct:</h3>
<div class="w3-code notranslate htmlHigh">
<p>This is a paragraph</p><br>
<p>This is another paragraph</p></div></div>
<div class="w3-example">
<h3>Wrong:</h3>
<div class="w3-code notranslate htmlHigh">
<p>This is a paragraph<br>
<p>This is another paragraph</div></div>
<hr>
<h2>XHTML Empty Elements Must Always be Closed</h2>
<p>In XHTML, empty elements must always be closed, like this:</p>
<div class="w3-example">
<h3>Correct:</h3>
<div class="w3-code notranslate htmlHigh">
A break: <br /><br>
A horizontal rule: <hr /><br>
An image: <img src="happy.gif" alt="Happy face" /></div></div>
<div class="w3-example">
<h3>Wrong:</h3>
<div class="w3-code notranslate htmlHigh">
A break: <br><br>
A horizontal rule: <hr><br>
An image: <img src="happy.gif" alt="Happy face"></div></div>
<hr>
<h2>XHTML Elements Must be in Lowercase</h2>
<p>In XHTML, element names must always be in lowercase, like this:</p>
<div class="w3-example">
<h3>Correct:</h3>
<div class="w3-code notranslate htmlHigh">
<body><br>
<p>This is a paragraph</p><br>
</body></div></div>
<div class="w3-example">
<h3>Wrong:</h3>
<div class="w3-code notranslate htmlHigh">
<BODY><br>
<P>This is a paragraph</P><br>
</BODY></div></div>
<hr>
<h2>XHTML Attribute Names Must be in Lowercase</h2>
<p>In XHTML, attribute names must always be in lowercase, like this:</p>
<div class="w3-example">
<h3>Correct:</h3>
<div class="w3-code notranslate htmlHigh">
<a href="https://www.w3schools.com/html/">Visit our HTML tutorial</a></div></div>
<div class="w3-example">
<h3>Wrong:</h3>
<div class="w3-code notranslate htmlHigh">
<a HREF="https://www.w3schools.com/html/">Visit our HTML tutorial</a></div></div>
<hr>
<h2>XHTML Attribute Values Must be Quoted</h2>
<p>In XHTML, attribute values must always be quoted, like this:</p>
<div class="w3-example">
<h3>Correct:</h3>
<div class="w3-code notranslate htmlHigh">
<a href="https://www.w3schools.com/html/">Visit our HTML tutorial</a></div></div>
<div class="w3-example">
<h3>Wrong:</h3>
<div class="w3-code notranslate htmlHigh">
<a href=https://www.w3schools.com/html/>Visit our HTML tutorial</a></div></div>
<hr>
<h2>XHTML Attribute Minimization is Forbidden</h2>
<p>In XHTML, attribute minimization is forbidden:</p>
<div class="w3-example">
<h3>Correct:</h3>
<div class="w3-code notranslate htmlHigh">
<input type="checkbox" name="vehicle" value="car" checked="checked" /><br><input type="text" name="lastname" disabled="disabled" /></div></div>
<div class="w3-example">
<h3>Wrong:</h3>
<div class="w3-code notranslate htmlHigh">
<input type="checkbox" name="vehicle" value="car" checked /><br><input type="text" name="lastname" disabled /></div>
</div>
<hr>
<h2>Validate HTML With The W3C Validator</h2>
<form method="get" action="https://validator.w3.org/check" target="_blank">
<p>Put your web address in the box below:</p>
<p><input name="uri" size="60" value="https://www.w3schools.com/html/html_validate.html" style="max-width:100%"/></p>
<p><input type="submit" value="Validate the page"></p>
</form>
<br>
<br>
<div class="w3-clear nextprev">
<a class="w3-left w3-btn" href="html_urlencode.asp">❮ Previous</a>
<a class="w3-right w3-btn" href="html_forms.asp">Next ❯</a>
</div>
<div id="mypagediv2" style="position:relative;text-align:center;"></div>
<br>
</div>
<div class="w3-col l2 m12" id="right">
<div class="sidesection">
<div id="skyscraper">
<div id="adngin-sidebar_top-0"></div>
</div>
</div>
<style>
.ribbon-vid {
font-size:12px;
font-weight:bold;
padding: 6px 20px;
left:-20px;
top:-10px;
text-align: center;
color:black;
border-radius:25px;
}
</style>