1. How Woven Fabric Crosses Threads and Knitted Fabric Links Loops
Woven fabric is made by crossing two sets of threads, the warp and the weft, at right angles [2]. The three basic weaves are plain, twill, and satin [2]. The denim used for jeans is a twill.
Knitted fabric is made by forming loops with one or more threads and linking each new loop to the previous ones. By definition, the threads are not crossed in straight lines, which is the difference from woven fabric [3]. The structure of loops linked one after another is a difference in how the thread is connected, separate from the thickness of the thread or the kind of fiber.
There are two families of knitting: weft knitting, which is hand knitting turned into a machine, and warp knitting, which applies the principle of weaving [3]. In theory, weft knitting can make a whole fabric from a single thread [4]. That is why a hand-knitted sweater can be made from one length of yarn.
2. Why a Knit Stretches Without the Thread Stretching
A 2018 paper in Physical Review X by Poincloux and colleagues introduces knitted fabric as something that, unlike woven fabric, is loose, extremely stretchy, and almost without stiffness. It then points out that the roughly 100% stretch of a scarf cannot be explained by the few percent stretch of the thread [1]. Here "100%" is the paper's "order of 100%," a rough guide to the size of the effect and not an exact ratio.
The answer the paper gives lies in the shape of the stitches. A curved stitch can deform a great deal, and the thread can also slip into the neighboring stitch. So the fabric stretches a lot while the way the stitches are connected, their topology, stays the same [1]. The thread itself hardly stretches. What changes is how the thread bends and how it is distributed between stitches.
Woven fabric, in contrast, is described as not stretching much in the lengthwise and crosswise directions [5]. It seems likely that the crossing threads hold each other in place.
One caution: the paper studied a model of a knit made from a single thread in the plain stitch described in the next section. It was not a study that measured the cloth of store-bought clothes, so the result should not be applied as is to every knit.
3. What Is the Jersey Stitch Used for T-Shirts, and Where Does Its Japanese Name Come From?
The stitch common in T-shirts is called the jersey stitch (also stockinette, or plain knit), the most basic knitting structure. It is thin and stretches well sideways. On the front the stitches line up vertically, and the back looks rougher [6].
The front and back are not symmetrical. This fabric tends to curl strongly at the top and bottom edges toward the front, and at the left and right edges toward the back. This is said to be because the threads linking vertical stitches lie mostly on the front side, and the threads linking stitches side by side lie mostly on the back side [4]. Curling edges are a sign that the structure of the stitches is not the same on both sides.
In Japan this stitch is called tenjiku, and the name comes from woven fabric. In old Japan India was called Tenjiku, and plain-woven cotton imported from India was called tenjiku cloth. One explanation says that this name became established in the knitwear trade as another name for the plain stitch [6]. The source words it tentatively, so it is best taken as "one explanation."
4. Why Does Woven Fabric Stretch Diagonally, and How Did People Use It?
Woven fabric does not stretch much along the warp and weft, but in the diagonal direction between them (the bias) it stretches and shrinks far more easily and moves in a flowing way [7]. The Knitting article also says that woven clothing stretches mainly in this diagonal direction [4].
People have used this property for a long time. In medieval Europe, long leg coverings called hose were made by cutting woven fabric on the diagonal so that they fit the legs closely. Italian tailoring of the 14th and 15th centuries also shows full-length leg coverings cut from woven cloth on the bias [7] [8].
The periods overlap, however. It is not the case that everything was woven before knitting appeared (see the next section).
5. When Did Knitted Socks and the First Knitting Machine Appear?
The Victoria and Albert Museum (V&A) says that knitted stockings were more comfortable and fitted better than those made of woven cloth [9]. Compare this with the bias-cut hose of the previous section. It can be read as one aim, a close fit to the leg, achieved by woven cloth through cutting and by knitted cloth through structure.
The records on the knitting side are also old. The oldest knitted items that can be confirmed are said to be cotton socks of about the 11th century found at the Fustat site (in present-day Cairo), Egypt, although the date varies by source [4]. The famous Egyptian sock of the 3rd to 5th century, with a split toe, was made not by knitting but by nalbinding, a different technique that makes loops with a single needle [10]. Not every old sock is knitted.
The first mechanical knitting machine, the stocking frame, was invented in 1589 by William Lee of England, who came from Calverton near Nottingham [11].
6. Why Does a Run Spread Along a Knitted Stocking?
Knitted fabric can come undone when a thread is pulled. A run (also called a ladder) in a stocking starts from a cut thread or a dropped stitch, and the connections between stitches break one after another [4] [12]. That one thread's loops are linked to form the cloth is the source of its stretchiness, and it can also be seen as the other side of how easily it comes undone.
A 2026 paper on how ladders spread has been posted to arXiv [12]. It may be a preprint that has not yet been peer reviewed, so here we only mention that physicists are studying it as a subject.
Not all knits come undone easily. Tricot and other fabrics made by warp knitting are said to resist runs [4].
7. How Does Spandex Make Even Woven Fabric Stretch?
Spandex is an elastic fiber invented by Joseph Shivers, a chemist at DuPont, in the late 1950s (sources differ between 1958 and 1959). It was developed as a replacement for heavy rubber thread in girdles and other foundation garments, and it can stretch to about five times its original length and return [13] [14].
It is blended in small amounts with cotton or polyester and goes into both woven and knitted fabrics. If the thread itself is made of a stretchy material, even woven fabric becomes stretch fabric. It is estimated that about 80% of the clothing sold in the United States in 2010 contained spandex [14]. This is an estimate for the United States in 2010, not for Japan or for today.
To sum up, there are two ways a fabric can stretch. One is structure: the shape of the stitches and the passing of thread between them (section 2), and the diagonal deformation of woven fabric (section 4). The other is material: the thread itself stretches. Stretch fabric, woven or knitted, is cloth with the second added to the first.
8. How Can You Test Stretch Yourself, and Where Can You Read the Sources?
There is one thing you can try. Gently pull fabrics around you lengthwise, crosswise, and diagonally, and compare them. Make a prediction first, then compare it with how the cloth actually stretches. Do not pull hard, and stay within what will not damage the cloth. If you have stretch jeans, look on the tag for the name of the stretchy thread.
Another way in is to read the sources themselves. The introduction of the paper by Poincloux and colleagues [1] can be read free on arXiv (arXiv:1801.08355), and you can compare how it describes the scarf with the wording of this article. The V&A page on the history of hand knitting [11] follows the story up to the invention of the knitting machine. Both are in English.