A bomb is a evice that generates and releases its energy very rapidly. The explosion creates a violent, very destructive shock wave. Bombs cause destruction and injury to objects and living things within the blast radius by the crushing action of the shockwave (pressure) and by mechanical impact of fragments, including shards of the bomb casing (often called "shrapnel") or objects from the surrounding area propelled by the blast. Bombs have been used for centuries in both conventional and unconventional warfare. Most bombs do not contain more energy than ordinary fuel, except in the case of a nuclear weapon.