Lesson 1

What Is XML?

Understand XML structure and common developer use cases.

XML (Extensible Markup Language) describes structured data with nested elements, optional attributes, and human-readable tags. Unlike JSON's braces, XML uses opening and closing tags:

<project>
  <artifactId>demo-app</artifactId>
</project>

Where developers still meet XML

Maven / Gradle POM files for Java builds
Android manifests and resource XML
SVG vector graphics embedded in apps or docs
Sitemaps, RSS/Atom feeds, and legacy enterprise configs

JSON and YAML dominate new APIs, but XML remains entrenched in mobile, Java, and publishing pipelines.

Well-formed vs valid

Well-formed — tags match, attributes are quoted, one root element. Parsers require this.
Valid (optional) — conforms to a schema such as XSD. Many day-to-day tools only check well-formed syntax.

DevCove's formatter focuses on well-formed XML you can prettify, validate, and minify locally.

Key takeaway

XML is a text envelope for structured data. The next lessons cover namespaces, Maven/Android patterns, and how to debug parse failures quickly.

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