Software Development

What is XML?

Quick answer

Extensible Markup Language: a text-based format that uses custom tags to structure, store, and exchange data.

XML, explained

XML became a W3C recommendation in 1998. It looks similar to HTML, but instead of predefined tags for display, XML lets you define your own tags that describe data, such as a post element containing title and author elements. Documents must follow strict rules, and schemas can define exactly which elements and attributes are allowed.

XML was the dominant data exchange format for many years and is still widely used in enterprise systems, office document formats, RSS and Atom feeds for blogs, SVG graphics, sitemaps for search engines, and many configuration files. For web APIs, JSON has largely replaced it because it is lighter and easier to work with in JavaScript, but XML remains valuable where validation is important.

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