A walking foot has been described well enough here, but thought that I would add that you don't need one if you have a Pfaff machine as it has a built - in one and I have also found that my Brother's pin - feed system works just as well and it is the best quilting machine that i have. So, I think you should test out whether you need one or not before you go to the expense of buying one. They are very useful for even feeding of material on some machines in my opinion.