XML and HTML are both markup languages. While they may sound similar, they’re unique languages with different applications. However, the two markup languages work together in several ways, and both are important to understand if you want to become proficient in web development. Here’s everything you need to know about XML vs HTML.
This article explores what XML and HTML are, when you use them, the differences between them, and how you can combine them to create an effective network.
What Is XML?
XML stands for Extensible Markup Language, and it’s one of the most common web languages used for transporting data across applications and servers.
Unlike other markup languages, XML itself does not do anything on its own. All it does is store data. It needs to interact with another application to display, move, or otherwise use the stored code.
XML does have syntax, but all its tags are defined by you, which you can also add or remove. This is what makes it “extensible.”
When Is XML Used?
XML’s primary function is in storing and transporting data. Much like HTML, XML is also used in creating websites, but unlike HTML, it isn’t concerned with displaying the data to your visitors.
XML’s only function is to move data around; how it then gets used is up to you and the technologies you pair it with. Usually, you’ll be transporting data from your server or another application to the database.
WordPress uses the REST API to establish a connection between servers, which can transfer data, including XML. In the past, it used XML-RPC instead, but that’s now outdated.
The type of data XML stores is entirely up to you, but usually, it’s used for “structured data” such as documents, invoices, catalogs, books, and so on. It’s often used to store data in web applications such as forms.
XML is platform-agnostic, and in plain text format, so you don’t need to worry about being unable to open and read data transferred to you. XML will work with basically any technology. That’s why it’s still so widely used today.
Features of XML
Here’s a breakdown of XML and what it can do, so you can easily compare it to HTML.
- XML efficiently stores and carries data from place to place.
- While it is generally human readable, XML relies on other applications to display, analyze, or output the data. It only stores and moves it.
- XML is platform-agnostic and can hook into any application that supports it.
- It is comparatively simple, easy to write and learn – though putting it to use is a big step up from HTML.
- XML is dynamic and can be used to create non-static web pages.
- XML tags are user-defined. You don’t need to memorize the tags like HTML; you make them up yourself.
- It’s an extensible language that can have information written to or removed from it at any time.
Examples of XML
Still confused? Let’s break down a simple example of XML in action.
<catalog>
<plant>
<id>01</id>
<name>Daisies</name>
<price>$2.95</price>
</plant>
<plant>
<id>02</id>
<name>Buttercup</name>
<price>$2.30</price>
</plant>
</catalog>The first thing to note: All of these tags are user-defined. There is no “catalog” tag built into XML, nor does it have any inherent functionality.
This is different from HTML, where a tag like <title> will affect the formatting of your text. In XML, tags do not do anything on their own.
As you can see, this is simply a way of sorting and cataloging information. The top-level tag is <catalog>, which applies to the entire document. Next, there is the <plant> catalog, and nested within it is information such as ID, name, and price for two different flowers.
On its own, this does nothing. But you could use this data to create a dynamic catalog that displays on your website and updates automatically as you modify the original XML.
You could dig into the HTML and update your website every time you add or remove a flower from your catalog, but this method is far more efficient. All it would take is a little setup to save a lot of work.
What Is HTML?
HTML stands for HyperText Markup Language, and it’s one of if not the most common web languages in the world. HTML is the unrivaled building block of the internet and the standard language for website creation.
If you want to learn front-end development, HTML is not optional. Almost 100% of websites use it and CSS. XML is a reasonably popular markup language, but HTML completely surpasses it.
Luckily, XML vs HTML are not competitors. You can use them together to accomplish great things.
When Is HTML Used?
HTML is the primary language used for coding the front end of a website. While it’s commonly used alongside and integrates with other languages like CSS, XML, and back-end languages such as Ruby and Python, HTML is the primary language responsible for crafting a website’s layout and basic appearance.
The way it works is by using various elements called tags to describe the structure and layout of a page. These are very similar to XML tags, but unlike XML, the tags are predefined; you need to memorize them and have a built-in function.
These tags are written in a document in your server, and visitors’ browsers then convert the HTML to a visual display. HTML creates images, videos, tables, or even entire page layouts.
For example, the HTML tag <b> will bold text when displayed in your browser. See the example below for a more thorough explanation.
Features of HTML
What is HTML in a nutshell? Here are the basics.
- HTML is one of the simplest coding languages out there, and it’s an excellent first step for beginner web developers who want to learn code.
- It is the primary, standardized language for web development. It is platform-agnostic and works in all browsers and applications that support it.
- HTML uses a simple markup syntax made of tags and attributes. These tags are predefined.
- HTML is not case-sensitive and will display even with typos and syntax errors.
- It creates static web pages that don’t update or change.
- HTML can integrate with other web languages such as CSS, XML, and back-end languages.
Examples of HTML
As already mentioned, HTML is just a series of elements called tags. These consist of an opening and closing tag that encloses text. Text within HTML tags might be bolded, italicized, made into a header, and so on.
Here’s an example:
<p>This is a paragraph</p>
The <p> tag sets a simple paragraph of text. It doesn’t do much on its own, but you can use CSS to style the <p> tag universally. Then every paragraph on your site will look the way you want.
Here are a few other basic HTML tags:
<h1>,<h2>, etc.: Sets a heading for the page. Goes up to<h6>.<body>: Sets the body text for the page.<b>: Bold text.<i>: Italicize text.<img src=”url.jpg”>: Display an image.<a href=" example.com">: Link to a page. The text enclosed in the tags will be your anchor text.<br>: Adds a line break. This is one of the only HTML tags that does not need a closing tag.
Like XML, HTML elements can be nested inside each other. For example, lists are a bit special; you need to use either the <ol> (ordered list with numbers) or <ul> (unordered list with bullets). Each list element receives the <li> tag.
<ul>
<li>Item #1</li>
<li>Item #2</li>
<li>Item #3</li>
</ul>
HTML elements also have “attributes” that further customize the tag. Here’s an example with the <img> tag:
<img src=”image.png” width=”1000” height=”600”>This creates an image with those dimensions. The “src” or source attribute calls for either an external link or a file on your server, while the width and height attributes can be any number.
Finally, here’s an example of a fundamental HTML document.
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<h1>H1 Heading</h1>
<p>Page Text</p>
</body>
</html>
The <!DOCTYPE html> and <html> tags define the document as an HTML document. Nested in <html> is <head>, with the page title within it. And then, the <body> tag contains a heading and some example text. The document is then closed off. Always remember to close all your HTML tags!
Differences Between XML vs HTML
HTML and XML are both markup languages, similar to but distinct from programming languages in that they use tags to annotate a document. They also use similar syntax, such as opening and closing tags.
But the similarities end there; these two web languages are very different in application.
HTML code is specifically made to design web pages for display in browsers. XML is meant only for data transport and storage. While it is human-readable, it isn’t meant to be seen in the front end.
While HTML is static, XML is dynamic. Sites made with HTML generally will not change or update on their own, while XML is almost always used to produce dynamic applications.
HTML is a fully predefined markup language with tags and elements already defined. You cannot make up your own HTML tags. XML is more like a framework for markup languages, with tags entirely made by you.
Finally, XML is far more strict in formatting, while HTML is more flexible and will attempt to render incorrectly formatted code. XML is case sensitive, will not parse without closing tags, must be nested in the proper order, and attribute values must be in quotes.
Any text editor can edit HTML or XML, though specialized code editors exist for each.
How Do HTML and XML Work Together?
As XML does not do anything on its own other than store and transport data, you need to work with other technology like HTML to get it to do anything.
If you have any sort of data that updates over time, such as a store catalog, a weather service, or a list of invoices from your store’s financial transactions, this is a prime integration for XML and HTML.
With just HTML, you need to go into the code and update your site every time anything changes. This is either far too time-consuming or downright impossible in some cases.
Instead, you could implement XML to separate this data from the HTML. Set up some application to collect the data, output it to an XML file, and then send it to your server, where your HTML formats it and updates the page as needed.
In other words, XML serves as the bridge between your site and another application. It’s one of many ways to automate your website and make it dynamically update.
Of course, there are plenty of ways to implement XML. That’s just one simple example of what it can do.
Pros and Cons of XML vs HTML
If you’re designing a website, HTML is essentially unavoidable. You can use many other languages, but HTML is the backbone of web design, and it has no other alternatives.
The good thing is that it’s relatively easy to learn. Coding syntax is straightforward and flexible when you make a mistake, and it’s mostly just a matter of memorizing what each tag does.
Of course, designing HTML that follows modern coding standards is another matter entirely, but this is true of every programming language. As far as the basics go, HTML is very approachable.
On the other hand, this means it’s not a very powerful language, and it’s tough to design something that’s beautiful or has complex functionality with only HTML.
These shortcomings are solved by CSS, Javascript, and so on, but HTML is still a static and simple language that should only be used for setting up a site’s basic layout and structure rather than as a complete web design tool.
Now the pros and cons of XML:
XML is very efficient at what it does, which is transporting documents and data between applications or servers. It’s a dynamic language that you can use to work with web applications and automate processes on your site.
Depending on what it’s used for, it’s a little more human-readable than HTML and somewhat easy to learn since it uses a similar coding syntax. Since all tags are user-defined, you don’t need to memorize anything.
But the hard part of XML is applying it. While it’s pretty easy to create a basic HTML document once you know the tags, putting XML to actual use requires more knowledge of web development.
Its code is also redundant, making it harder to read and write and results in larger file sizes that require more storage and network space.
Summary
HTML and XML are both different languages that perform various functions, so it’s not a case of choosing one or the other, but instead using them when most appropriate.
In short, HTML is the primary building block of web development and is used to define the structure of a page. XML can transport data between servers and is often used alongside HTML or other applications.
Now that you know the basics, it’s time to give HTML and XML a try for yourself. Check out our list of web development tools to get started.
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