What is Gluten-free Flour?

I've been baking since I was a kid. I created my first recipe when I was in elementary school because I hated raisins, but I loved oatmeal cookies. If only oatmeal cookies didn't have raisins, I figured, they would be perfect. It was just so hard to find raisinless oatmeal cookies that I decided to take matters into my own hands, and I created a band-new recipe, one that didn't appear in Betty Crocker. I made oatmeal cookies with chocolate chips. I was really ahead of my time. Watch out, Betty Crocker! Now, to be fair my Mom must have helped me out with this quite a bit - Betty Crocker should watch out for my mom, too! - but I was always the kind of kid who asked a lot of question. Why? How was that invented? Where does this come from? My mom and me after going gluten-free. The mother-daughter team from Joy of Cooking may now step aside! I always had the exotic notion that everything came from medieval Europe. Mayb...