Paul Wilson writes:  "I've even noticed that nearly everyone, including Scott Guthrie and Fritz Onion, incorrectly refers to Virtual Directories when what they really mean is IIS Applications.  These terms are not interchangeable -- you can have a Virtual Directory without it being an IIS Application, and you can also have an IIS Application without it being a Virtual Directory.  Being a Virtual Directory is not relevant to ASP.NET -- its just a logical way to organize your web-site and physical directories.  "

Good point Paul, I think I've mixed them up myself when talking about this stuff.