In this article, we will examine HTML XHTML. A stricter version of HTML, known as XHTML, is based on XML and uses many more XML tags and elements.
What is XHTML?
- It is an acronym for Extensible HyperText Markup Language.
- The XHTML specification is a stricter version of HTML based on XML
- HTML is defined as an XML application in XHTML
- All major browsers support XHTML
- HTML Versus XHTML:
- What is XHTML?:
- Why XHTML?:
- What makes HTML different from XHTML.:
- XHTML – <!DOCTYPE ….> Is Mandatory:
- XHTML Elements Must be Properly Nested:
- XHTML Elements Must Always be Closed:
- XHTML Empty Elements Must Always be Closed:
- Lowercase is required for XHTML:
- Attribute names must be lowercase in XHTML:
- Quote all XHTML attribute values:
- Attribute minimization in XHTML:
- Advantages of XHTML Versus HTML:
Documents in XML must be adequately marked up (be “well-formed”).
A browser will also display the website even with errors in HTML markup when it has errors in HTML. In other words, XHTML has a much stricter error-handling system.
It was developed to make HTML more extensible and flexible (so it could be used in conjunction with XML, for example).
What makes HTML different from XHTML.
- <!DOCTYPE> must be specified.
- HTML must contain the xmlns attribute.
- <html>, <head>, <title>, and <body> must be included.
- Lowercase elements are always required.
- Lowercase is required for all attribute names.
- Quote all attribute values.
- There is no room for attribute minimization.
- A properly nested element is always required.
- Ensure that all elements are closed.
XHTML – <!DOCTYPE ….> Is Mandatory
To be considered HTML XHTML, the document must have an XHTML <DOCTYPE> declaration.
This XHTML document contains the bare minimum of tags needed:
XHTML Elements Must be Properly Nested
The following is an example of proper nesting of elements in XHTML when it comes to HTML XHTML:
<html><body><b><i>Keep eye on opening and closing tags</i></b></body></html>
XHTML Elements Must Always be Closed
A closed element in XHTML must look like this:
XHTML Empty Elements Must Always be Closed
When we talk about HTML XHTML then, XHTML requires empty elements to be closed, as follows:
Lowercase is required for XHTML
It is always necessary to use lowercase names for element names in XHTML, as shown here:
Attribute names must be lowercase in XHTML
It is mandatory to always write attribute names in lowercase in XHTML, such as this:
Quote all XHTML attribute values
To use XHTML, attribute values must be quoted in the following way as it comes to HTML XHTML:
Attribute minimization in XHTML
The following attributes are not allowed to be minimized in XHTML:
Example:  Incorrect Syntax
Advantages of XHTML Versus HTML
XHTML (Extensible Hypertext Markup Language) and HTML (Hypertext Markup Language) are both markup languages used for creating web pages. XHTML is a stricter and more standardized version of HTML. Here are some advantages of XHTML over HTML:
- Well-Formedness: XHTML documents must be well-formed, meaning that they follow a strict set of rules for syntax and structure. This makes it easier to write and maintain web pages and helps to avoid errors.
- Consistency: Because XHTML is a more standardized version of HTML, it provides greater consistency across different web browsers and devices. This means that web pages will look more consistent across different platforms.
- XML-based: XHTML is based on the XML (Extensible Markup Language) standard, which allows for greater flexibility and extensibility. This means that web developers can create their own custom tags and attributes.
- Compatibility: XHTML is backward compatible with HTML, meaning that XHTML documents can be displayed in web browsers that support HTML. This makes it easy to transition from HTML to XHTML.
- Accessibility: XHTML provides better support for accessibility features, such as screen readers, than HTML. This makes it easier for people with disabilities to access web content.