What is an XML?

XML predates JSON as the dominant data-interchange format on the web and is still the backbone of many enterprise systems, SOAP web services, and document formats like DOCX and RSS feeds under the hood. Unlike JSON, XML supports attributes on elements, namespaces to avoid tag-name collisions across combined documents, and a formal schema language (XSD) that can rigorously validate a document's structure before it's ever parsed by application code. This makes XML well suited to environments, such as finance and healthcare EDI, where strict, auditable document contracts matter more than developer convenience. The tradeoff is verbosity and parsing overhead: the same data typically takes more bytes and more processing to handle in XML than in JSON, which is why JSON dominates modern REST APIs. But XML remains unavoidable when integrating with legacy enterprise systems, government data exchanges, or older SOAP-based APIs, so any integration platform still needs a competent XML parser and serializer in its toolkit.