Bomb

A bomb is a military device that a destructive effect on a target, destroying itself in the process. The bomb may be manually placed on a target, or dropped from the air onto it. There is a means of triggering the effect (i.e., detonation) under conditions desired by the user of the bomb.

Moving the bomb to the target

The device does not have any type of active propulsion, either internal to it such as a rocket engine, or imparted to it externally, as by the rapid combustion of a propellant in an artillery piece. Destructive devices that are actively propelled are called warheads. Gravity bombs are dropped from aircraft.

Control of the effect

It also has a means of deciding when to trigger the effect, such as a fuze or a communications link over which a triggering signal is received (i.e., command detonation. Gravity bombs, for example, may have fuzes that act immediately on contact with the target, or delay slightly so the bomb casing can penetrate into the target. A bomb may have a proximity fuze so that it detonate at some altitude above the ground.

Before the 20th century, bombs did include externally propelled shells such as a bursting mortar shell. In the United States' national anthem, "The Star-Spangled Banner", the "bombs bursting in air" refer to shells fired from British warships in Baltimore Harbot, which exploded in the air over Fort McHentry.

Effect

The effect is most commonly explosive blast, but could be intense heat (i.e., incendiary, blast and small pieces of fast-moving metal (e.g., blast-fragmentation, or a nuclear exlosion. Bombs may release chemical warfare or biological warfare agents.