Hook and loop was originally manufactured from cotton but in order for the fastener to last longer, a stronger material was needed. Eventually the cotton was switched out for nylon and polyester to improve the lifespan of the fastener.
Almost all hook fasteners are manufactured via weaving. Woven products are created by interlacing several longer threads, known as the warp, with several crossing threads, known as the weft. This is done on a machine called a loom. This video explains how the loom functions to mass produce large quantities of complex designs. For the manufacturing of hook, there is an additional step that requires the loops that are woven into the material to be cut, creating the hooks. This can be seen in the picture above.
For the loop side, most fasteners are woven, although some are knitted instead. The knitting process differs slightly from the weaving process. Where a weave is interlaced, a knit is connected by a series of loops. There is only one set of yarn needed for knitting. Knitting has several active loops at one time on the knitting needle waiting to interlock with another loop, while weaving is just interlacing lengths of yarn. This results in a product that is a little more elastic and a little less stable than a woven one.
Prior to the Industrial Revolution, manufacturing textile products was a tedious, time-consuming task undertaken by individual artisans. This meant that textiles were quite valuable. Inventions in the 1700s such as the spinning jenny and water-powered cotton mill accelerated the rise of the textile industry. The steam engine, power loom and mule spinner were introduced in the 1800s, which further hastened the growth of the textile industry. With the advent of the Industrial Revolution, mass production allowed textile manufacturing to become a mainstream industry and greatly reduced the costs of these products. When synthetic fibers were developed in the 1900s, the textile industry was revolutionized again. Rayon, nylon and polyester became valuable materials within the industry, replacing cotton, silk and wool as the primary source materials. This helped reduce costs further by eliminating the high costs of those animal and plant products.
Today, China is the largest exporter of textiles, followed by India, Italy and Germany. Most hook and loop is manufactured in China and Taiwan, while the Velcro companies operate in several countries including the United States.