Single crochet in the back loop is a variation of the basic single crochet stitch. When working in the back loop, instead of inserting the hook under both loops of the stitch from the previous row, the hook is inserted only under the back loop of the stitch. This creates a different texture and appearance in the finished project, with a raised ridge running along the back of each row. Single crochet in the back loop is often used in projects such as ribbing, cuffs, and edging, as it creates a stretchier and more flexible fabric than single crochet worked through both loops.