In knitting

Knitting

Knitting is a method by which thread or yarn may be turned into cloth or other fine crafts. Knitted fabric consists of consecutive rows of loops, called stitches. As each row progresses, a new loop is pulled through an existing loop. The active stitches are held on a needle until another loop can...

, ribbing is a pattern in which vertical stripes of stockinette stitch

Basic knitted fabrics

A few types of knitted fabric are so fundamental that they have been adopted as part of the language of knitting, similar to techniques such as yarn over or decrease...

 alternate with vertical stripe

Stripe

Stripe or Stripes may refer to:* Stripes * Stripes * S.T.R.I.P.E., a fictional superhero* Striper, a fish* Stripes Convenience Stores* Data striping, a data storage technique...

s of reverse stockinette stitch

Basic knitted fabrics

A few types of knitted fabric are so fundamental that they have been adopted as part of the language of knitting, similar to techniques such as yarn over or decrease...

. These two types of stripes may be separated by other stripes in which knit and purl stitch

Stitch (textile arts)

In the textile arts, a stitch is a single turn or loop of thread or yarn. Stitches are the fundamental elements of sewing, knitting, embroidery, crochet, and needle lace-making, whether by hand or machine...

es alternate vertically; such plissé stripes add width and depth to ribbing but not more elasticity

Elasticity (physics)

In physics, elasticity is the physical property of a material that returns to its original shape after the stress that made it deform or distort is removed. The relative amount of deformation is called the strain....

.

The number of knit and purl stripes (wales) are generally equal, although they need not be. When they are equal, the fabric

Fabric

A fabric is a textile material, short for "textile fabric".Fabric may also refer to:*Fabric , the spatial and geometric configuration of elements within a rock*Fabric , a nightclub in London, England...

 has no tendency to curl, unlike stockinette stitch. Such ribbing looks the same on both sides and is useful for garments such as scarves.

Ribbing is notated by (number of knit stitches) x (number of purl stitches). Thus, 1x1 ribbing has one knit stitch, followed by one purl stitch, followed by one knit stitch, and so on.

Ribbing has a strong tendency to contract laterally, forming small pleat

Pleat

A pleat is a type of fold formed by doubling fabric back upon itself and securing it in place. It is commonly used in clothing and upholstery to gather a wide piece of fabric to a narrower circumference....

s in which the purl stitches recede and the knit stitches come forward. Thus, ribbing is often used for cuff

Cuff

A cuff is an extra layer of fabric at the lower edge of the sleeve of a garment covering the arms. In US usage the word may also refer to the end of the leg of a pair of trousers...

s, sweater

Sweater

A sweater, jumper, pullover, sweatshirt, jersey or guernsey is a garment intended to cover the torso and arms. It is often worn over a shirt, blouse, T-shirt, or other top, but may also be worn alone as a top...

 hem

Hem

To hem a piece of cloth is to sew a cut edge in such a way as to prevent unraveling of the fabric.There are many different styles of hems of varying complexities. The most common hem...

s and, more generally, any edge that should be form-fitting. The elasticity depends on the number of knit/purl transitions; 1x1 ribbing is more elastic than 2x2 ribbing, etc.
However, some cable patterns may "pull in" more than ribbing (i.e., have a smaller gauge

Gauge (knitting)

In knitting, the word gauge is used both in hand knitting and machine knitting; the latter, technical abbreviation GG, refers to "Knitting Machines" fineness size. In both cases, the term refers to the number of stitches per inch, not the size of the finished garment...

); in such cases, a ribbed border may flare out instead of contracting.

Slip stitch

Slip-stitch knitting

Slip-stitch knitting is a family of knitting techniques that use slip stitches to make multiple fabrics simultaneously, to make extra-long stitches, and/or to carry over colors from an earlier row.-Basic methods:...

es may be added to increase the depth of the ribbing, and to accentuate the stitches of certain wales. For example, the knit stitches can be slipped every other row to double their height and make them come forward.

Ribs can be decorated with nearly any motif used for a plain knitted fabric, e.g., bobbles

Bobble (knitting)

In knitting, a bobble is a localized set of stitches forming a raised bump. The bumps are usually arranged in a regular geometrical pattern or may be figurative, e.g., represent apples on a knitted tree....

, cables

Cable knitting

Cable knitting is a style of knitting in which textures of crossing layers are achieved by permuting stitches. For example, given four stitches appearing on the needle in the order ABCD, one might cross the first two the next two, so that in subsequent rows those stitches appear in the new order...

, lace

Lace knitting

Lace knitting is a style of knitting characterized by stable "holes" in the fabric arranged with consideration of aesthetic value. Lace is sometimes considered the pinnacle of knitting, because of its complexity and because woven fabrics cannot easily be made to have holes...

, various color

Color

Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

s, and so on.