Zipper is a fastening device consisting of parallel rows of metal, plastic, or nylon teeth on adjacent edges of an opening that are interlocked by a sliding tab.
How Zipper Works (Mechanism of Zipper):
As zipper has two rows of teeth on each side facing one another & each one of the teeth has a hook and they are offset from one another so as they are pulled towards one another to connect in sequence. A zipper is closed when the hooks into those hollow areas. In order for this to happen each of the teeth and hollows must be identical in size and shape. The slide portion of the zipper contains wedges that push the hooks and hollows together at specific angles to close it. In order to unzip the closure the pull is pushed against the hooks in the opposite direction and detaches the teeth. The stops at each end of the zipper are what keep the pull from sliding completely off the tracks of teeth.