What are the key differences between XML and JSON, and which is preferred for web APIs?

JSON is compact and maps straight onto JavaScript data, while XML is more verbose but supports attributes, comments, and richer schema validation — and for web APIs, JSON usually wins.

The same data shows the contrast. In XML a list of relatives needs a repeated tag for each item:

<relatives>
  <relative>Grandpa</relative>
  <relative>Marge</relative>
</relatives>

In JSON it's just an array, and converting it into program data is direct:

{ "relatives": ["Grandpa", "Marge"] }

For web APIs JSON is typically preferred — smaller payloads and effortless JavaScript integration. XML still appears in enterprise systems, document formats, and standards (like SOAP) where its attributes and strict schemas earn their keep.