We all know the old adage that a picture speaks a thousand words. Well, we go one step further. Many design agencies will tell you what they intend to build, or will just show you mock-up pictures. That approach can still lead to misinterpretation and misunderstanding. Instead, we'll actually build an interactive prototype you can play with in a browser to show you HOW our solution will work.
At this stage it is not about how it looks, but how it will function and how it's structured. So it won't be pretty (and it's not meant to be), but it gets us very close to what you want very quickly.
See here for an example prototype.