HTML VS XHTML
What is XHTML?
XHTML stands for EXtensible Hypertext Markup Language. It was developed by World Wide Web Consortium (W3C) in early 2000.
XHTML is pretty much similar to HTML, but it is very strict than HTML. For example in HTML if you don’t close some tags still your code will run. But if you are creating an XHTML page and forget to close some tags, your code will won’t run. Also there are many elements that are mandatory to add in XHTML. These are:
Mandatory to Add in XHTML
- <!DOCTYPE>:- If you are creating a XHTML web page, it’s mandatory to declare document type.
- attribute xlmns:- In XHTML it’s mandatory to add xlmns attribute in the <html> tag.
- Elements like
<html>,<head>,<title>and<body>are mandatory to add. - All tags must be closed.
- Elements always must be properly nested.
- Elements and Attribute names always must be in lowercase letters.
- Attribute values always must be quoted.
- Attribute minimization is prohibited.
Explanation
XHTML – <!DOCTYPE….>
Whenever you create any new XHTML document, It’s mandatory to declare document type.
The XHTML document must also include some mandatory elements like, <html>, <head>, <title> and <body>. The xlmns attribute must also be present in <html> tag. The attribute xlmns specify the xml namespace for the document.
In an Example below this is how a simple XHTML document looks like.
Example
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Title of document</title> </head> <body> <p> main content </p> </body> </html>
Elements in XHTML Must be Properly Nested
Elements in XHTML must always be properly nested. For example:
Right:
<b><i>your text</i><b>Wrong:
<b><i>your text</b></i> All XHTML Elements Must only be in Lowercase
In XHTML, all element names must only be in lowercase. If we write an element name in uppercase the code will won’t run. For example:
Right:
<head>
<title>
</title>
</head>Wrong:
<head>
<title>
</title>
</HEAD>Similarly, all attribute names must be in lowercase only.
Attribute Values in XHTML Must Always be Quoted
Whenever you use an attribute in XHTML, you must Quote it’s value. For example:
Right:
<a href="https://crus4.com/web-development/"> Learn Web Development for free </a> Wrong:
<a href=https://crus4.com/python/> Learn Python Programming for free </a> XHTML Attribute Minimization is Prohibited
Attribute minimization is prohibited in XHTML. For example:
Right:
<input type="checkbox" name="books" value="Atomic Habits" checked="checked" />
<input type="text" name="lastname" disabled="disabled" />Wrong:
<input type="checkbox" name="books" value="Atomic Habits" checked />
<input type="text" name="lastname" disabled />Why Use XHTML?
There are various reasons why we should use XHTML. Some of them are listed below:
- It’s mandatory to close all tags in XHTML. This makes our code clean and easy to understand.
- XHTML is used to define quality standard web pages.
- It’s validate with standard XML tools.
- XHTML code can easily be converted into PDFs.
- XHTML is supported by almost all major browsers.
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