Extensible Markup Language

What is a Document Type Declaration in XML?

Learn what exactly a Document Type Declaration is in XML and all possible ways you can use it.

What is a DTD (Document Type Definition) in XML?

Learn what a DTD (Document Type Definition) is in XML.

When is a XML document valid?

To be valid, an XML document must to meet some requirments. You can find a list of these requirments right here: is well-formed and valid according to the…

When is XML document well-formed?

Example of a well-formed XML document <?xml version="1.0"?> <solar-system> <stars> <star>Sun</star> </stars>…