In Clara Parkes' The Knitter's Book of Yarn, she takes about "buckets" into which all yarns fall. These include protein fibers, cellulose fibers, cellulosic fibers, and synthetic fibers. We agree that these are the overarching categories. But when searching for and buying yarn, sometimes it's helpful to have these categories broken down even further. That's what we've attempted to do with the following categories.