We've defined prototype as an approximation of an artifact on one or more dimensions of interest and that last bit of that phrase, One or more dimensions of interest, suggests that a prototype need not necessarily approximate the artifact on all it's dimensions. And in fact, it's useful to think about. Two extremes. At1 extreme Protatechs can be very focused on one or a few dimensions of interest at the other extreme, they can be comprehensive and that is, essentially capture most or all of the aspects or dimensions of the artifact. Let me give you an example. I was designing a, a battery pack for an electric bicycle and I was very interested in using these cells, these lithium cells, that were made, that are made by A123, and, I was also interested in the idea of using a bicycle water bottle as the storage container, for the battery pack. That would give us the ability to use the water bottle cage on a bicycle to hold the battery pack. The question I want answered was, how many of these, A one, two, three, cells would fit in a standard water bottle? Now, of course, you could do that mathematically. And you could maybe even use a three dimensional computer model, But instead I chose to simply make some models of battery cells out of a wooden dowel that I bought at the hardware store, that are very close in dimension to the A123 cells. And that let me play with the configuration and packing of those cells in a very real way, without having the precarious task of working with live lithium batteries that contain a lot of energy. And in, in fact I was able to figure out how to pack the cells that, in fact, five will fit, in a row, but not six. In a standard water bottle back and to do that very efficiently and, and quickly. This however is not a comprehensive prototype, Of course I can't power my electric bicycle with this battery pack. It's focused, in the sense that it only approximates the artifact on one dimension of interest and that is its physical shape, which allows me to answer only one of the many questions that I might be concerned with respect to this artifact. . On the other, At the other, On the other hand let me just show you an example of a comprehensive prototype. It's what we normally, I think, we think of as a prototype. This is an example of a media shelf that I've designed for my house. I wanted one that was fairly shallow in depth that would clear a door and not take too much room in the, Not take too much space in the room. I was having a hard time finding a standard product, So I designed one myself. And I built a simple prototype with using less that $ten worth of materials, that I was able to buy at the home improvement store, I was able to answer most of the questions of concern, including communicating to my wife and children what that media stand would look like and how it would fit. And on the basis of that comprehensive prototype, was able to go ahead and proceed to design the actual final artifact that is now on the house. So that's an example of a comprehensive prototype, as distinct from a focused prototype. . A second distinction that I want to make is between physical and analytical prototypes. Not all prototypes have to be physical. Now, of course, a prototype of a digital good, like a website or a service product like a car rental system. Those aren't going to be physical prototypes because the artifact itself isn't physical. But even for an artifact that is physical, even for the design of such a physical artifact. The prototype need not be physical and it can take on an analytical form. So, let me give you some examples of, of analytical and physical. My colleague and friend David Robertson was designing a new kitchen for his house and he was concerned with how it would feel, what the shapes would be like, how the configuration would work, A so he built a cardboard kitchen, which is shown here which has the shapes of all the, the, the cabinets and the counters and where they would all go. That was very useful. That's an example of a focused, physical prototype. When I designed my own kitchen, I took a different approach and I designed my kitchen in a digital illustration tool, modeling tool, called Google SketchUp, Which by the way, is freely available if any of you want to use it. It's quite easy to learn as well. But, here's my kitchen designed in Google SketchUp and that was very useful as a way to analytically describe the kitchen. And let me answer many other questions about the kitchen. Now, of course, that's not a physical prototype. It's an analytical prototype, But still useful in communicating and in understanding what the kitchen would look like, and how it might work. So in some prototypes might, may be focused or comprehensive, They may be analytical or they may be physical. Any of those approaches, can still be an approximation of the artifact on one or more dimensions of interest and therefore satisfies our definition of a prototype.