The <any> element enable us to extend the XML document with elements not specified by the schema.

The following example is the fragment from an XML schema called "family.xsd". It shows a declaration for "person" element. By using the <any> element we can extend (after <lastname>) the content of "person" with any elements:

Now we want to extend the "person" element with "children" element. In this case we can do so, even if the author of the schema above never declared any "children" elements.

Look at this schema file named "children.xsd":

The XML file below (called "Myfamily.xml"), uses component from two different schemas; "family.xsd" and "children.xsd":

The XML file above is valid because the schema "family.xsd" allow us to extend the "person" element with an optional element after the "lastname" element.

The <any> and <anyAttribute> elements are used to make EXTENSIBLE document! They allow documents to contain additional element that are not declared in the main XML schema.