For standard crochet patterns, the hook is worked under both loops of the top of the stitch. However, there are instances where you might want to work under the front loop only (FLO) or back loop only (BLO) when working on a crochet project. In this video, Jen Lucas demonstrates how to crochet through the front loop only and the back loop only.
Jen begins by showing a swatch of fabric where she worked through the back loop only when on the Right Side (RS) and worked through the front loop only when on the Wrong Side (WS). All the stitches were worked in single crochet. By working through only a single loop in this manner, the resulting fabric has horizontal lines, creating a bit of texture and interest.
Once Jen reviews the standard single crochet working under both loops of the stitch, she then demonstrates how to work through the back loop only. She brings the hook through the center of the “V” at the top of the stitch to bring the hook under the back loop. She then works a single crochet stitch. She repeats several single crochets through the back loop only.
Turning the swatch to come to the Wrong Side, Jen begins working through the front loop only. She brings her hook to the front of the piece and brings it up through the center of the “V” at the top of the stitch to catch the front loop only. She then works a single crochet. She repeats several single crochets through the front loop only.
This video uses US crochet terminology.