What is XML?
XML (Extensible Markup Language) is a human-readable, machine-interpretable format used to structure, store and exchange data between systems. It uses tags, similar in concept to HTML, yet unlike HTML, XML doesn’t define how information should be displayed. Instead, it defines what the data is. This separation of content from presentation makes XML a long-standing standard for interoperability across applications, platforms, and industries.
Although newer formats like JSON are common today, XML remains foundational for enterprise workflows, document standards, API integrations, and configuration files due to its precision, extensibility, and rigorous schema validation.
How does XML work?
To understand how XML functions, you should understand its core building blocks. XML represents data using custom, nested tags that describe each piece of information. Tags must be well-formed, properly closed, and follow a strict hierarchy. This structure ensures data is easy to parse and validate.
XML also supports attributes, namespaces, and schemas (XSD) to clarify meaning, avoid naming conflicts, and enforce rules. Schemas define which elements are allowed, what data types they must contain, and how they relate to one another. This guarantees consistency across systems that exchange XML documents.
When applications process XML data, they typically use parsers—such as DOM, SAX, or streaming readers—to extract values, validate the structure, or convert the XML into objects or other formats. Because XML is platform-agnostic, any system that can read text can interpret XML.
Why has the XML format become so important?
XML continues to play a role in enterprise environments for several reasons. First, it supports highly structured, strongly validated data. Teams that require contract-based data interoperability—such as banking, healthcare, government, and telecom—depend on XML’s schema enforcement to prevent errors and maintain data integrity.
Second, XML’s extensibility allows organisations to add new fields or data types without breaking existing systems. This makes it suitable for long-lived standards like SAML (for identity), SOAP (for web services), and Office Open XML (used in Microsoft Office documents).
Finally, XML offers deep support for metadata and hierarchical representation, making it ideal for document interchange, configuration management, and machine-to-machine communication.
Key capabilities
Custom tags and extensibility – Organizations define their own element names and structures to match business needs.
Schemas for validation – XSD allows precise control over data types, hierarchies, and rules.
Namespaces – Prevent naming conflicts when combining data from multiple sources.
Platform-neutral format – Compatible with virtually all programming languages.
Hierarchical structure – Ideal for representing nested or complex data relationships.
Rich metadata support – Attributes, comments, and processing instructions provide contextual information.
Wide tooling ecosystem – Editors, validators, transformation engines, and parsers exist across all enterprise platforms.
Enterprise platforms continue to rely on XML even as lighter formats, such as JSON (JavaScript Object Notation), YAML (YAML Ain’t Markup Language), and Protocol Buffers (Protobuf), grow in popularity.
Microsoft
Azure services support XML for configuration, service definitions, and SOAP-based integrations. Microsoft Office formats—including .docx, .xlsx, and .pptx—are built on XML containers.
AWS
Amazon S3, CloudFormation, and IAM policies historically supported XML-based formats. Many partner integrations in enterprise ecosystems still rely on XML for structured payloads.
Google Cloud
Google supports XML for document transformations, data ingestion pipelines, and integrations with legacy enterprise systems.
Security and identity platforms
Standards such as SAML (identity federation), XACML (access control), and STIX/TAXII (threat intelligence) rely heavily on XML.
Use Cases of XML
Exchanging structured data between financial systems.
Defining identity federation assertions using SAML.
Storing application configuration files for servers or middleware.
Structuring documents in Office Open XML formats.
Using XSLT to transform XML into HTML, JSON, or other formats.
Transmitting SOAP-based web service requests.
FAQs about XML
Q: How is XML different from HTML?
HTML defines how content is displayed, whereas XML defines the structure and meaning of data.
Q: Is XML still used today?
Yes. While JSON is common for modern APIs, XML remains essential in enterprise systems, identity standards, configuration management, and regulated industries.
Q: Does XML require schemas?
No, but using XSD greatly improves consistency, validation, and interoperability.
The Takeaway
XML remains a critical foundation for structured, validated, and interoperable data exchange, especially in enterprise systems where precision and long-term stability matter. Its extensibility, schema support, and platform neutrality ensure XML continues to support identity, configuration, integration, and document standards across modern IT environments.
