What does Xml Validating Reader class do?
The XmlTextReader class does not validate the contents of an XML source against a schema. The correctness of the XML documents can be measured by two things is the document well formed and is it valid or not. The Well-formed means that the overall syntax is correct. The Validation is much deeper which means is the XML document is proper with respect to the schema defined.
Therefore the XmlTextReader only checks if the syntax is correct but does not do any validation. There's where the XmlValidatingReader class comes into picture. So this again comes at a price as XmlValidatingReader have to check for DTD and Schema's there are slower as compared to the XmlTextReader.