XML Namespaces Explained

What are XML Namespaces?

Namespaces prevent naming conflicts when combining XML from different sources. They qualify element names with a unique prefix tied to a URI.

The Problem

<!-- Two "table" elements with different meanings -->
<table><tr><td>Cell</td></tr></table>  <!-- HTML table -->
<table><name>Coffee Table</name></table>  <!-- furniture -->

The Solution: Prefixes

<root xmlns:h="http://www.w3.org/1999/xhtml"
      xmlns:f="https://furniture.example.com">
  <h:table><h:tr><h:td>Cell</h:td></h:tr></h:table>
  <f:table><f:name>Coffee Table</f:name></f:table>
</root>

Default Namespace

<book xmlns="https://books.example.com">
  <title>No prefix needed here</title>
</book>

FAQs

Is the URI a real web address?

No — it's just a unique identifier. It doesn't need to resolve to anything. More in our XML guides.

When do I need namespaces?

When mixing vocabularies (e.g. SVG inside XHTML, or SOAP envelopes).