Extensible Markup Language

• Semi-structured data (well-structured)
  • Document format (well-formed)
• Self-describing

{xml}<book author="C. Darwin">The Origin of Species</book>

• Tag: {xml}<book>,</book>
• Attribute: {xml}author="C. Darwin"
  • ID: id is a special attribute that is unique
• Namespace: definition of your schema

<myNS:book xmlns:myNS="http://.../mySchema"> 
	<myNS:title>...</myCitationStyle:title>
	<myNS:author>...</myCitationStyle:author>...
</book>

• Elements: The Origin of Species
• {xml}<![CDATA[Tags: <book>,…]]> means character data (escape not required)
• Tree Representation
• Use XPath and XQuery to query it