what is bunker

A bunker is a defensive military fortification designed to protect people and valuable materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. They are usually made of reinforced concrete and provided with embrasures. Bunkers can also be used for industrial purposes such as mining sites, food storage areas, dumps for materials, data storage, and sometimes living quarters. When a house is purpose-built with a bunker, the normal location is a reinforced below-ground bathroom with fiber-reinforced plastic shells. In golf, a bunker is a sand trap or embankment constituting a hazard on a golf course. The verb "to bunker" can mean to fill a ships bunker with coal or oil, or to place or store something in a bunker.