public static void Main()
<h1>This is <b>bold</b> heading</h1>
<p>This is <u>underlined</u> paragraph</p>
<h2>This is <i>italic</i> heading</h2>
var htmlDoc = new HtmlDocument();
var node = htmlDoc.DocumentNode.SelectSingleNode("//body");
foreach (var nNode in node.Descendants())
if (nNode.NodeType == HtmlNodeType.Element)
Console.WriteLine(nNode.Name);