This pattern is a top-down sock knit on two circular needles.

From the web site - Knit both socks at once from the top down on two circular needles. Use either stockinette (shown) or ribbing for the leg. Ribbing provides a snugger but stretchy fit, a good solution if the calf circumference of the recipient is unknown. Slip stitch heel provides added comfort. Optional contrasting color for cuff, heel and toe. This very basic pattern can be easily adapted for different textures or stitch patterns.