How to Knit Ribbing
Ribbing forms a stretchy band and is usually found at the bottoms of sweaters, sleeves, neckbands, hat brims and mitten cuffs, and at the tops of socks. When worked as an edging, ribbing is generally worked with smaller needles than the main body of the garment to keep the edges firm and elastic.
Ribbing can be worked as K1, P1 ribbing; K2, P2 ribbing; or any combination of stitches that will be specified in the pattern.
With ribbing, you are lining up the stitches so the knit stitches always look like they are on top of knit stitches and the purl stitches always look like they are on top of purl stitches.
Knit 1, Purl 1 Ribbing (K1P1)
Knit a stitch. Bring the yarn forward to the front of the work between the left and right needle.
Purl the next stitch.
Return the yarn to the back of the work between the needles.
Knit the next stitch.
Alternate Knit and Purl stitches until the row is finished (or for however many stitches the pattern specifies).
At the end of the row:
If you have an even number of stitches in the row, start the pattern again with a knit stitch.
If you have an odd number of stitches in the row, start the pattern again with a purl stitch.