This special knit construction uses the addition of a second yarn within the same stitch. The second yarn is generally of a different color or type. During the knitting process the second yarn is placed under the first yarn, so that each yarn can be rolled to a specific side of the fabric. In many cases, one yarn/color appears on the face of the fabric, and the other yarn/contrast color appears on the back. A specialty version of this knit fabric is created by alternating a series of knit and purl stitches. (See the checked pattern in the Plaited Fabric swatch.)