Hook and loop fasteners or "touch fasteners" are what most people commonly know as Velcro. Velcro is a brand name which first appeared in 1948, although the name is often casually used to refer to other similar products. The name Velcro comes from the French vel for velvet and cro for crochet, as in hook.
Hook and loop fasteners are generally made of two strips, one with loops, and one with pieces that "hook" onto the other strip. Some applications use loops on both sides. Either type of fastener system is used to hold things together and is available in different colors, generally black, white, and beige, although other colors can be special ordered. Hook and loop fasteners are also available in different lengths, widths, and shapes.
The most popular type of hook and loop fastener comes in strips with an adhesive backing. There are also rolls of hook and loop fastener, broken up into smaller sections, with the paper that covers the adhesive also cut, making it easier to pull away small pieces as needed. Another type is the "coin" style -- small, circular pieces of hook and loop fastener, which also have an adhesive backing. Hook and loop fasteners are made from a variety of materials, including polyester, nylon, and high heat and fire resistant materials. They are also available in different strengths, as well as with a variety of different adhesives, depending on the purpose for which the fastener is intended.
There are also sew-on hook and loop fasteners for fabric applications. This type is very convenient for garment and fabric treatment construction. It is much simpler to install than other types of fasteners and closures, such buttonholes or zippers. Hook and loop fasteners are also popular in shoe designs, especially for small children that have yet to learn how to tie their shoes but still want to dress on their own.
There are many handy uses for hook and loop, but its main disadvantage is that when the strips are not closed, hooks and loops often collect lint, hair, and other small particles of debris. Cleaning the fasteners regularly is the best defense, but that's a small price to pay for such convenience.