This is the opposite of the problem. For any non-trivial application, the user needs to understand the data model they are working with. They don't need to kno

This is the opposite of the problem. For any non-trivial application, the user needs to understand the data model they are working with. They don't need to know the gritty details of how things are encoded and enumerated, but they do need to be aware of the entities and their relationships. This is true for any kind of user, savvy or not. Deep usability problems happen when the application omits, hides or distorts aspects of the model that the user is manipulating. For example: - inline formatting codes in word processors - fake folders in filesystems e.g. My Documents - "apply" button in dialogs - wizards Design should start with the user model, then create the user interface to manipulate it. The internal model can be different from the user model but they should have a one-to-one mapping.