Hello.edmx file that the Wizard created is a text file that contains the XML definition of the model. In earlier versions of the Entity Framework the designer was rather limited, and there were things (rather a lot of things) that you had to do directly in the XML. That’s less true with every release, and we won’t be working directly with the XML very much in this book.
If you want to look at the raw XML, you can do so by right-clicking the file in the Solution Explorer and choosing XML (Text Editor) from the dialog:
On Your Own ...