XML and HTML – Similar but Different

XML (Extensible Markup Language) and HTML (HyperText Markup Language) share several similarities because they both stem from SGML (Standard Generalized Markup Language), a standardized system for organizing and tagging elements of a document.

Let’s take a look at XML and HTML and discuss some key aspects here.

Starting with similarities, they both use tags to encase data. This means that both languages utilize opening and closing tags to surround and denote content components.  

For instance, in HTML, you would use <p> to start a paragraph and </p> to end it. XML uses a similar system, where <tag> starts a section and </tag> ends it. Additionally, both languages support attributes within these tags, which provide additional information about the elements.  

Differences between XML and HTML

However, there are significant differences between XML and HTML. The most important difference lies in their purposes.

HTML is designed for displaying data and focuses on how the data looks. It has predefined tags with specific meanings that browsers can interpret to render web pages. For instance, <p> denotes a paragraph, and <img> denotes an image.

On the contrary, XML is primarily used for storing and transporting data, emphasizing what the data is. It doesn’t have predefined tags, allowing users to create custom tags most appropriate for their data, which can help make the data self-descriptive.

XML’s Flexibility versus HTML’s Standardization

Another significant difference lies in the flexibility offered by XML versus the standardization of HTML.

Because XML allows users to create their tags, it is incredibly flexible and adaptable. This makes it suitable for various applications, including complex data interchange between applications.

However, this flexibility can also make it harder to work with, as there is no standard way to represent particular data types.  

Conversely, HTML’s predefined tags make it easier to use, particularly for creating web pages. Still, they limit its use to applications with appropriate predefined tags.  

Error Handling in XML and HTML

Finally, XML and HTML have different strategies for error handling.

XML is designed to be very strict, and a single error, such as a missing closing tag, will cause an XML parser to stop working. This ensures that XML data is always well-formed and error-free. HTML, however, is designed to be more forgiving. 

Browsers will attempt to render HTML pages even if there are errors, making the best guess about the developer’s intent. This robustness allows web pages to display even when there are mistakes in the HTML, but it can also lead to inconsistent results across different browsers.

XML and HTML – 3 mins