What is XHTML? What are the similarities and differences with HTML? What are its uses? Do those who plan to learn website design and programming need to learn XHTML?

In this context, we answer these questions and introduce you to XHTML. The audience of this content is those who know and have worked with the HTML markup language. To understand XHTML and the main reasons for its development, it is necessary to be familiar with HTML, XML, and markup languages.

What is XHTML?

Extensible HyperText Markup Language (Extensible HyperText Markup Language) is an extended version of the HTML markup language to give it the privileges and capabilities of the XML markup language. XML or Extensible Markup Language (extensible markup language) is a markup language, just like HTML, which was created and released shortly after.

Markup languages are not programming and scripting languages in the strict sense of the word. Markup languages are designed and built to store and transfer information through the Internet and between different systems. These languages are used to categorize document information (the contents of a website page) and structure it into different parts. Using these languages, information is written so that browsers (computers/machines) can read and display structures and information in specified formats to the user.

It’s true that HTML and XML have many similarities and are both built on the Markup Language (SGML) standards, but they also have some very important differences. One of the most important differences between these two markup languages is that the XML language is designed so that both humans and any type of machine and system can read it. But HTML is not like that.

The HTML language has more tags and it can be said that it is a bit more complicated compared to the first example. XML is simpler and makes it easier to store and transfer information. XML is simpler because, unlike HTML, it does not have defined tags.

For this reason, this language is called extensible because the developer can define any tag according to his needs and add it to the written code. If the developer adds new items with new tags to the information stored in XML, different systems have no problem reading the new tags.

What is particularly important in this language is that the structure and rules are completely respected. XML has stricter writing rules (syntax) to ensure code readability and orderly and transparent structure. For this reason, whenever those rules are not followed, no part of the code will be executed and displayed.

XHTML is a markup language that is built based on XML rules and is a version of HTML that is written with XML rules so that, unlike HTML, it is extensible and compatible with different systems and types of languages.


XHTML is an extensible version of the HTML language, which has more precise and strict writing rules to ensure the orderly and transparent structure of information and ensure that no mistakes are made. XHTML was created to improve the performance of HTML and help developers design and develop websites more easily, quickly, and without errors.

Unlike HTML, XHTML does not have defined tags. Also, it does not allow the browser to execute the code if there is a syntax error. This is while the browsers execute the HTML codes of a website page despite the errors and bugs in the markup (general structure). This may cause the overall structure and formatting of a page to not be displayed correctly.

Next, we will examine the similarities and differences of these two languages separately.

Similarities of XHTML and HTML

The similarities between XHTML and HTM are:

  • These two languages have a similar structure. Both are markup languages and use < > tags to define the structure and content of a web page.
  • Both languages support the <a> tag to create hyperlinks between web pages.
  • Both languages support multimedia elements (elements) and can be used to insert multimedia elements such as images, videos, and sounds into web pages.
  • Most web browsers support these two languages and will read and run web pages written in them.
  • Both XHTML and HTML are compatible with CSS language, and CSS (Cascading Style Sheets) is used to add color and style and make the visual effect of content and pages made with these two languages more attractive.
  • Both languages can be used to develop website pages and web applications.

Differences between XHTML and HTML

The differences between XHTML and HTML are:

  • The following tags are required in XHTML: <html>, <head>, <title> and <body>.
  • In XHTML, elements must be nested properly.
  • In XHTML, element and attribute names must be written in lowercase letters.
  • Codes written with XHTML have better readability and are more organized because writing with this language has stricter rules.
  • If the tags are not properly closed the values are not enclosed in ” ” or the attributes are not written completely, the XHTML code has errors and the coder must fix them.
  • XHTML has more uses than HTML. The most important use of HTML is in the development of the main structure and overall formatting of static and dynamic websites. But XHTML has other uses.

Applications of XHTML markup language

The XHTML markup language is also used in the following cases:

  • Server-side development and coding with PHP or Python scripting languages.
  • Creating website user interfaces (Web UIs) using frameworks such as Bootstrap.
  • Building mobile user interfaces (Mobile UIs) using frameworks such as jQuery Mobile,
  • development of online games,
  • Making forms and
  • Writing and developing XML documents to transfer data between different applications and systems.


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