The annotations are used in a xml document to provide additional information about the xml document. The annotation element can be followed by a documentation element to make it understandable to a user (human). In case an annotation element is followed by an appInfo element then the information is meant to be used by an application.
Example of an annotation followed by document element:
<xsd:element name=”books”>
<xsd:annotation>
<xsd:documentation xml:lang=”en”>
This is a collection of best-selling books.
</xsd:documentation>
</xsd:annotation>
</xsd:element>