If a document is syntactically correct it can be called as well-formed XML documents. A well-formed document conforms to XML's basic rules of syntax:

•     Every open tag must be closed.
•    The open tag must exactly match the closing tag: XML is case-sensitive.
•    All elements must be embedded within a single root element.
•    Child tags must be closed before parent tags.
•    A well-formed document has correct XML tag syntax, but the elements might be invalid for the specified      document type.