In sewing and dressmaking, a ruffle, frill, or furbelow is a strip of fabric, lace or ribbon tightly gathered or pleated on one edge and applied to a garment, bedding, or other textile as a form of trimming. A ruffle without gathers or pleats may also be made by cutting a curved strip of fabric and applying the inner or shorter edge to the garment.
Thank you Wikipedia
Want to know all there is to know about making and creating and manipulating ruffles? I highly recommend this fabulous book, The Art of Manipulating Fabric. I keep in close by and read it often. It will blow you away with all of the creative techniques inside or it might make you want to throw away your sewing machine entirely (that was my sister's response to the book :).
Off to dream of these gorgeous creations I have been coveting online...