Fasteners are used to create permanent and semi-permanent bonds between materials, as well as joints that can be opened and closed, and purely decorative additions. Zippers are an important and widely used type of fastener that were developed by Gideon Sundback in 1913 from an earlier invention for a fastener that used hooks and eyes. The invention was first referred to by the name zipper in 1923 by the B.F. Goodrich Company, who initially used them on rain boots. Zippers came into use for children's clothing and trouser flies, replacing buttons, in the 1930's. Today, zippers are used in clothing, outerwear, luggage, backpacks, automobiles, tents, and sleeping bags.
Zippers use two sets of interlocking teeth called chain zippers, or coils called coil zippers, each connected to a strip of fabric tape. The teeth or coils are formed of metal, plastic, or synthetic material. A slider with a tab, which may be purely functional or serve a decorative function as well, is used to open and close the zipper. Besides the details of the mechanism, there are several other ways of categorizing zippers.
Conventional zippers, whether chain or coil, are those in which the zipper apparatus shows. Such zippers have the two strips of fabric connected at one end and stops at either end to prevent the slider from running off the zipper. The bottom stop keeps a little bit of the zipper always zipped, and when the slider is pulled, the rest of the zipper follows along, gliding into place. When using a conventional zipper, a flap may be used to cover the mechanism, as is commonly found in jeans.
Invisible zippers, like conventional zippers, have the two strips of fabric connected at one end, but the zipper tape itself covers the zipper mechanism. They, too, have top and bottom stops, visible only on the reverse side.
Separating zippers are designed with a unique type of bottom stop so that the fabric tapes come apart, allowing, for example, the two sides of the front of a winter jacket to be separated for ease of use. The user inserts the bottom stop at the bottom of one fabric tape into the slider, which is on the other tape, thereby joining the two sides of the base together. The user then pulls the slider up to close the zipper. Most zippers have a differentiated front and back, but two-sided zippers were developed for items that are reversible, and are designed to be equally workable from either side.
Zippers often come with a sewing guideline marked in the fabric, and sewing and craft directions characteristically give clear instructions about any parameters to consider in choosing an appropriate zipper for the project. Zippers come with a wide variety of tape colors and in various lengths and thicknesses so that they may be appropriately matched to the need. There are also special heavy-duty zippers for the most demanding use.