An XML document must be contained in a single element. That single element is called the root element, and it contains all the text and any other elements in the document. In the following example, the XML document is contained in a single element, the <greeting> element. Notice that the document has a comment that's outside the root element; that's perfectly legal.

<?xml version="1.0"?>
<!-- A well-formed document -->
<greeting>
  Hello, World!
</greeting>
          

Here's a document that doesn't contain a single root element:

<?xml version="1.0"?>
<!-- An invalid document -->
<greeting>
  Hello, World!
</greeting>
<greeting>
  Hola, el Mundo!
</greeting>
          

An XML parser is required to reject this document, regardless of the information it might contain.