A plain knit is simply knitting each stitch on the front or public side of the fabric and purling each stitch on the back or private side of the fabric. This stitch is called stockinette stitch.
Garter stitch, where each and every row is knit across, regardless of whether you are working the front or back side, produces horizontal ridges that are somewhat similar to ribbing turned 90 degrees and somewhat stretchy, but not as stretchy as ribbing.
Ribbing is created by knitting a sequence of knit and purl stitches to create raised vertical ridges in the fabric which are especially elastic and well suited to cuffs and necks.
The most common ribbing patters are 1 x 1 and 2 x 2.
For 1 x 1 ribbing: *K1, P1, repeat from * across
For 2 x 2 ribbing: *K2, P2, repeat from * across
There are other combinations possible, such as 3 x 3 or 2 x 3 or what ever your heart desires, but 1 x 1 and 2 x 2 are the most commonly used rib patterns.
A plain knit is simply knitting each stitch on the front or public side of the fabric and purling each stitch on the back or private side of the fabric. This stitch is called stockinette stitch.
A rib knit is created by knitting 2 stitches, and purling 2 stitches, over and over.
Example: cast on 10 stitches.
knit 2,purl 2, knit 2, purl 2, knit 2
next row: purl 2, knit 2, purl 2, knit 2, purl 2
Repeat these rows for about 4 inches, and you'll see the rib knit pattern.
Another version of rib knit, is, knit 1, purl 1, knit 1, purl one.
You'll get the same pattern as above, just in more narrow rows.
Rib knit is commonly seen on sock cuffs, and sweater cuffs.