Zipper

A zipper, zip, fly, or zip fastener, formerly known as a clasp locker, is a commonly used device for binding the edges of an opening of fabric or other flexible material, such as on a garment or a bag. It is used in clothing (e.g., jackets and jeans), luggage and other bags, sporting goods, camping gear (e.g. tents and sleeping bags), and other items. Zippers come in all different sizes, shapes, and colors. Whitcomb L. Judson, who was an American inventor from Chicago, is sometimes given credit as the inventor of the zipper, but he never made a practical device. The method, still in use today, is based on interlocking teeth. Initially, it was titled the “hookless fastener” and was later redesigned to become more reliable. The bulk of a zipper consists of two rows of protruding teeth, which may be made to interdigitate, linking the rows, carrying from tens to hundreds of specially shaped metal or plastic teeth. These teeth can be either individual or shaped from a continuous coil, and are also referred to as elements. The slider, operated by hand, moves along the rows of teeth. Inside the slider is a Y-shaped channel that meshes together or separates the opposing rows of teeth, depending on the direction of the slider's movement. The word zipper is onomatopoetic, because it was named for the sound the device makes when used, a high-pitched zip. In many jackets and similar garments, the opening is closed completely when the slider is at the top end. Some jackets have double-separating zippers with two sliders on the tape. When the sliders are on opposite ends of the tape then the jacket is closed. If the lower slider is raised then the bottom part of the jacket may be opened to allow more comfortable sitting or bicycling. When both sliders are lowered then the zipper may be totally separated. Bags, suitcases and other pieces of luggage also often feature two sliders on the tape: the part of the zipper between them is unfastened. When the two sliders are located next to each other, which can be at any point along the tape, the zipper is fully closed.