Knitting is one of several ways to turn thread or yarn into cloth.
Unlike woven fabric, knitted fabric consists entirely of horizontal parallel courses of yarn. The courses are joined to each other by interlocking loops in which a short loop of one course of yarn is wrapped over the knot of another course.
Knitting can be done either by hand or by machine. In practice, hand knitting is usually begun by forming a base series of twisted loops of yarn on a knitting needle. A second knitting needle is then used to reach through each loop (or stitch) in succession in order to snag a knot of yarn and pull a length back through the loop. This forms a new stitch. Work can proceed in the round (circular knitting) or by going back and forth in rows.
Knitting can also be done by machines, which use a different mechanical system to produce nearly identical results. Originally a male-only occupation, the first knitting trade guild was started in Paris in 1527. Knitting became a household occupation with the growing popularity of knitted stockings and by the end of the 1600s, one to two million pairs of stockings were exported from Britain to other parts of Europe.
The two basic stitches are knit and purl. These two nominal stitches are actually identical, however, being the obverse and reverse of the same stitch. Typically, a knit stitch is formed by inserting the needle in the front of the loop (the left, as its on the needle) and pulling a loop of yarn forward to form a new loop, while a purl stitch is formed by inserting the needle in the back of the loop (the right) and pulling a loop of yarn backward.
A piece of knitting begins with the process of casting on, which involves the initial creation of the stitches on the needle. Different methods of cast on are used for different effects; one may be stretchy enough for lace, while another provides a decorative edging. Provisional cast ons are used when the knitting will continue in both directions from the cast on. The body of a knitted piece may include plain stitches or a number of color and textured patterns. The number of active stitches remains the same as when cast on unless stitches are added (an increase) or removed (a decrease) to shape the item. Many patterns can be made by using knit and purl stitches in various combinations. If only knits or only purls are used when working back and forth in rows, the result is called garter stitch. Alternating rows of knits and purls result in stockinette stitch, also known as stocking or jersey stitch, the stitch most often used in commercial garments such as T- shirts. Different combinations of stitches can be used to form ribbing, cables, or other textures. Complex patterns can be formed by knitting with multiple colors in either intarsia or Fair Isle techniques.
Once the knitted piece is finished, the remaining live stitches are cast off. Casting (or binding) off loops the stitches across each other so they can be removed from the needle without unravelling the item. Although the mechanics are different from casting on, there are a similar variety of methods and choices to be made. Knitted garments are most commonly made in pieces, where individual sections of the garment are knit separately and then sewn together once all the pieces have been completed. Seamless knitting, where a whole garment is knit as a single piece is also possible. Smaller items, such as socks and hats are usually knit in one piece on double pointed needles or circular needles. There are many regional styles of knitted garments with long histories, such as guernsey sweaters, jerseys, aran sweaters, and Fair isle patterning.
The classic knitting material is worsted-weight yarn spun from the wool of a sheep, though goats wool (mohair if it comes from an Angora goat), rabbit hair (angora if it comes from an Angora rabbit), and alpaca fur are also well-known. Natural fibres such as these have the advantage of being slightly elastic and very breathable, while trapping a great deal of air, making for a fairly warm fabric. Other natural fibers that can be used for yarn include silk, linen, and cotton.
These tend to be much less elastic than the animal-hair yarns, though they can be stronger in some cases. The finished product will also look rather different from the woolen yarns. A number of synthetic materials are also commonly made into yarn, chiefly acrylic. Acrylic yarn for a long time completely dominated the knitting market, and is still frequently the only available option at craft stores and other stores that do not specialise in knitting supplies.
However, there is currently a large community of knitters that prefer the feel of natural fibers, both during the knitting process and in the final product. 100% acrylic yarns are available, as are wool-acrylic blends in various proportions. Some other synthetics are available as well; yarn designed for use in socks frequently contains a small percentage of nylon, and numerous specialty yarns exist. A relatively recent trend in knitting yarn is the novelty yarn.
Typically these involve at least one or two strands of regular yarn twisted together with something else to make an interesting texture. The extra element can be a metallic thread, or a much-thicker or much-narrower strand of yarn, or yarn that varies between thick and thin. Eyelash yarn has short bits of plastic resembling glittery eyelashes sticking out at ninety degrees from the main strands of yarn, yielding a final knitted fabric that appears to be surrounded by a half-inch-thick cloud of fringe or fluff. Novelty yarns tend to have poor stitch definition. Ultimately, there is no restriction as to what materials can be used to knit; anything that can be viewed as a long strand of something can be used as a sort of knitting yarn. Creative knitters have successfully used ribbon, plastic strips, wire, string threaded with beads, and rope to make fashion bags, bowls, jewellery, household items, and works of art.