A bottle opener is a device that enables the removal of metal bottle caps from bottles. More generally, it might be thought to include corkscrews used to remove cork or plastic stoppers from wine bottles.
A metal bottle cap is affixed to the rim of the neck of a bottle by being pleated or ruffled around the rim. A bottle opener is a specialized lever inserted beneath the pleated metalwork, which uses a point on the bottle cap as a fulcrum on which to pivot.
There are several distinct designs of such bottle openers. Wall mounted openers are typically found behind bars in pubs, whilst hand-tool bottle openers tend to be found and used in domestic environments. Whereas the functional elements of bottle openers (a tooth or lip to catch the underside of the cap, a fulcrum across which to exert the force that will remove the cap, and usually a lever for mechanical advantage) tend to be consistent (sometimes the lever is the bottle itself), their aesthetic design is subject to very great variety, and a great many decorative types are available.