Some zippers have two sliders, allowing variation in the opening'ssize and position. In most jackets and similar garments, the opening is closed entirely when one slider is at each end. In most baggage, the opening is closed entirely when the two sliders are next toeach other at any point along the zipper.
increase or decrease the size of an opening to allow or restrict the passage of objects, as in the fly of trousers or in a pocket.
join orseparate two ends or sides of a single garment, as in the front of a jacket, dress or skirt.
attach or detach a separable part of the garment to or from another, as in the conversion betweentrousers and shorts or the connection / disconnection of a hood and a coat.
decorate an item.
These variations are achieved by sewing one end of the zipper together, sewing both ends together, orallowing both ends of the zipper to fall completely apart.
A zipper costs relatively little, but if it fails, the garment may be unusable until the zipper is repaired or replaced—which can be quitedifficult and expensive. Problems often lie with the zipper slider; when it becomes worn it does not properly align and join the alternating teeth. If a zipper fails, it can either jam (i.e. get stuck) orpartially break off.
 HistoryElias Howe, who invented the sewing machine, received a patent in 1851 for an "Automatic, Continuous Clothing Closure". Perhaps because of the success of his...