The purpose of XML Schema is to define the legal building blocks of an XML document, just like a DTD.

An XML Schema:

• defines element that can appear in a document
• defines attribute that can appear in a document
• defines which element is child element
• defines the order of the child elements
• defines the number of child element
• defines whether an element is empty or include text
• defines data types for an element and attribute
• defines the default and fixed values for elements and attributes

We think that very soon XML Schema will be used in most Web applications as a replacement for DTDs. Here are some reasons:

• XML Schemas are extensible to future addition
• XML Schemas are richer and more powerful than DTD
• XML Schemas are written in XML format
• XML Schemas support data types also
• XML Schemas also support namespaces

XML Schema became W3C Recommendation 02. May 2001.

You can read more about XML Schema standard in our W3C tutorial.

Before you goes to this tutorial you should have a basic understanding of the following:

• HTML / XHTML
• A basic understanding of DTD
• XML / XML Namespaces

If you are going to study these subjects first, find the tutorial on our Home page