Adding a textured heel flap is an easy way to make the socks more interesting AND to make the heel more durable at the same time.
The slip-stitch heel is super-easy, and it is also nice and stretchy – great if you’re not sure how big the sock-recipient’s ankle is.
Video: Slip-Stitch Heel Pattern
Slip-Stitch Heel Pattern:
Row 1 (RS): (Sl 1, k1) to last st, end k1.
Row 2 and all even rows: Sl 1, p across.