XML (XML)

The granddaddy of structured data formats that made everything look like an HTML page. Extensible Markup Language was once the undisputed king of data interchange, enterprise configuration, and basically anything that needed angle brackets to feel important. XML gave us the power to define our own tags, validate documents against schemas, and write transformation stylesheets. It also gave us carpal tunnel from typing all those closing tags.

In its heyday, XML powered everything from SOAP web services to RSS feeds to Java configuration files that were longer than the actual application code. Then JSON showed up with its minimalist syntax and stole the spotlight for web APIs. But don’t count XML out just yet. It’s still deeply embedded in enterprise systems, document formats like DOCX and SVG, Maven build files, and Android manifests. If you’ve worked in any large organization, you’ve probably inherited at least one XML file that no one dares to touch.

Why it matters: XML remains a critical part of the software ecosystem, especially in enterprise environments, document processing, and legacy integrations. Understanding XML is essential when working with established systems, and you’ll inevitably encounter it when dealing with SOAP services, CI/CD configurations, or that one build tool that refuses to move on.