These socks start out like a standard top-down sock, but things take a little twist when you get to the heel. Instead of setting half the stitches aside and working a heel flap on the other half, you’ll keep working in the round, increasing at the beginning and midpoint of the round to form the heel flap and gusset. Then you’ll switch to working in rows to turn the heel and work a bit of the sole. Finally, you’ll resume working in the round again to finish off the foot.
This construction is comfy and looks great, but it also eliminates the need to pick up stitches along the sides of the heel flap (a process that many knitters dislike). Also, if your socks tend to wear out under the heel (as mine so often do), you can easily carry a reinforcing thread along with your yarn when working the section in rows for added durability. If you’ve only ever made top-down socks with heel flaps in the past, this approach is a simple, nonthreatening way to branch out into another type of construction.