A bomb is an explosive object that makes and lets out its energy very quickly. This detonation makes a big shock wave. Bombs have been used for centuries. Some bombs also throw out dangerous metal fragments, and some are firebombs.
Most bombs do not contain more energy than ordinary fuel, except in the case of a nuclear weapon. However, they release their energy more quickly, thus are more powerful.
A bomb is usually some kind of container filled with explosive material that is designed to destroy things. The word bomb comes from the Greek word βόμβος (bombas), an onomatopoeic term with almost the same meaning as "boom" in English.
Air forces send bombers to destroy enemy targets. Terrorists use bombs in suicide attacks. Explosive materials used in mining work the same way, but are usually not called bombs.