What is the Difference Between DTD and XSD?

05/15/2025 • Felipe Moraes

The main differences between Document Type Definition (DTD) and XML Schema Definition (XSD) are as follows:

  1. Syntax: DTD is derived from SGML syntax, while XSD is written in XML.
  2. Datatypes: XSD supports datatypes for elements and attributes, while DTD does not.
  3. Namespaces: XSD allows support for namespaces, while DTD does not.
  4. Extensibility: XSD is extensible in nature, while DTD is not.
  5. Control on XML structure: XSD provides more control over the structure of an XML document compared to DTD.
  6. Usage: DTD is used to define a document type for SGML, while XSD describes the elements in an XML document.

In summary, DTD is an older technology that predates XML and is less capable than XSD. XSD offers more advanced features, such as support for datatypes, namespaces, and extensibility, making it more suitable for defining the structure of XML documents.

Comparative Table: DTD vs XSD

Here is a table comparing the differences between Document Type Definition (DTD) and XML Schema Definition (XSD):

Feature DTD XSD
Definition Defines the structure of an XML document Defines the structure and the vocabulary of an XML document
Namespaces Does not support namespaces Supports namespaces
Datatypes Does not support datatypes Supports datatypes
Syntax Derived from SGML syntax Written in XML
Extensibility Not extensible Extensible
Control on XML structure Less control on XML structure More control on XML structure

In summary, while both DTD and XML Schema are used to define the structure of XML documents, XML Schema is more powerful, expressive, and modern, supporting namespaces, datatypes, and extensibility, with a simpler and more extensible syntax. DTD has been deprecated in favor of XSD due to its limited usefulness and lack of support for namespace and datatypes.

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