How do you know if your XML document is well formed and valid? One way is to check it with an XML validator, and there are plenty out there to choose from. Validators are packages that will check your XML and give you feedback. Here's a list of some of the XML validators on the Web:
W3C XML validator (http://validator.w3.org/)— The official W3C HTML validator. Although it's officially for HTML, it also includes some XML support. Your XML document must be online to be checked with this validator.
Tidy (www.w3.org/People/Raggett/tidy/)— Tidy is a beloved utility for cleaning up and repairing Web pages, and it includes limited support for XML. Your XML document must be online to be checked with this validator.