Quilters love to swap fat quarters. When you buy a piece of fabric you usually ask for what you want in fractions of a yard. Given that in the United States high quality quilt fabric costs in the $10 per yard range, it's easy to see why buying one-fourth of a yard is a nice little bite of fabric. But if you asked for just one fourth of a yard, the fabric store would cut you a piece that is nine inches in length by 44-45 inches in width. This is not a very useful size of a piece of fabric, whereas if you ask for a fat quarter, they will cut half a yard (18 inches) and then cut that in half length-wise (to 22 or so inches), resulting in a nice little chunk to take home with you, swap with a friend or store in your fabric stash.