I've been asked a number of times where prototyping fits into the design/development process. A number of years ago I would have said after you do some design. At this year's IA Summit, Gene Smith was discussing the process they went through for designing a product for nForm. He talked about how he had prototyped some of the screens and then went back and did wireframes.

That's when I had one of those dejavu moments. That's exactly what I had done for a new product/service we're building for my company, Messagefirst. We had started talking about the design, then sketched out some screens. In the interest of getting things done (GTD), I decided to just prototype out some screens in HTML. Shortly after, I realized that some of the ideas in the sketches wouldn't work that well. So, I did some more prototyping and then went back in to flesh out some of the details with wireframes afterwards.

Where does prototyping fit into your design/development process?