XContainer.Nodes Method

public IEnumerable<XNode> Nodes()

XElement xmlTree = new XElement("Root",
    new XElement("Child1", 1),
    new XElement("Child2", 2),
    new XComment("a comment"),
    new XElement("Child3", 3),
    new XElement("Child4", 4),
    new XText("mixed content"),
    new XElement("Child5", 5)
);
IEnumerable<XNode> nodes =
    from nd in xmlTree.Nodes()
    select nd;
foreach (XNode node in nodes)
    Console.WriteLine(node);

<Child1>1</Child1>
<Child2>2</Child2>
<!--a comment-->
<Child3>3</Child3>
<Child4>4</Child4>
mixed content
<Child5>5</Child5>

XDocument xmlTree = new XDocument(
    new XComment("a comment"),
    new XProcessingInstruction("xml-stylesheet", "type=\"text/xsl\" href=\"hello.xsl\""),
    new XElement("Root",
        new XAttribute("Att", "attContent"),
        new XElement("Child1",
            new XCData("CDATA content")
        ),
        new XElement("Child2",
            new XText("Text content")
        )
    )
);

foreach (XNode node in xmlTree.Nodes())
{
    Console.WriteLine(node.NodeType);
    if (node.NodeType == XmlNodeType.Element)
    {
        foreach (XAttribute att in ((XElement)node).Attributes())
            Console.WriteLine(att.NodeType);
        foreach (XNode node2 in ((XElement)node).Nodes())
        {
            Console.WriteLine(node2.NodeType);
            if (node2.NodeType == XmlNodeType.Element)
                foreach (XNode node3 in ((XElement)node2).Nodes())
                    Console.WriteLine(node3.NodeType);
        }
    }
}

Comment
ProcessingInstruction
Element
Attribute
Element
CDATA
Element
Text