using AngleSharp.Html.Parser;
var config = Configuration.Default;
var context = BrowsingContext.New(config);
var source = @"<h3> This is a simple title </h3>
<p>Lorem ipsum <b> dolor sit </b> amet consectetur, <i>adipisicing elit.</i> </p>
var parser = context.GetService<IHtmlParser>();
var document = parser.ParseDocument(source);
Console.WriteLine(document.DocumentElement.TextContent);