Medium Format Refers to film size. There are many sizes to choose from within this definition, but currently the most common are 120, and 220.
I shoot this format because the cameras are just amazing. They range from "toy cameras" to Professional Level, and everywhere in between. I am currently shooting with the Mamiya RB67 Pro-S and the FPP Debonair, and I am currently searching for a Rangefinder style camera. In this collection, there are images from both the Mamiya RB and the Film Photography Project's "Toy" camera, the Debonair. Can you tell which one goes to what image?