Lesson
well-formed
This lesson teaches Well-formed documents—the ideas, syntax, and habits you need before moving on in XML.
Forms are where users convert and where security mistakes (validation, labels) show up first.
You will apply Well-formed documents in contexts like: Enterprise integration, publishing pipelines, Android resources, and data exchange alongside JSON.
Edit XML in the playground, watch well-formedness feedback, preview rendered output, then complete the quizzes.
When the previous lesson's MCQs feel easy and you can explain Well-formed documents in your own words.
A parser accepts well-formed XML before any schema check. Common errors: unclosed tags, duplicate attributes, invalid characters, or multiple roots.
Use the playground validator — red messages point to parser errors.
Challenge
Done when: Validation panel shows green well-formed message.
Can you explain this lesson in 30 seconds without reading notes?
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Multiple choice — immediate feedback.
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