火药又被称为黑火药，是一种早期的炸药，直到17世纪中叶都是唯一的化学爆炸物。火药一般由硫磺、木炭和硝石（硝酸钾）混合而成，其木炭是作为燃料，而硫磺和硝石作为氧化剂。由于火药的燃烧特性和能大量产生气体和热量，火药被广泛用作枪械中的发射药和烟花中的烟火药。

学术界一般认为火药发明于7世纪的中国，是中国术士为炼制长生不老药而得到的副产品。早在唐代的《太上圣祖金丹秘诀》里，就有了早期****的书面记载。火药的发现导致了烟花的发明和早期火药武器在中国出现。随后火药武器也陆续在阿拉伯、欧洲和印度出现。一般认为欧洲的火药技术是由阿拉伯人传播过去的。西方最早的有关火药的书面记录是由英国哲学家罗吉尔·培根于13世纪记录。

Gunpowder, also known as black powder, is the earliest known chemical explosive. It is a mixture of sulfur, charcoal, and potassium nitrate (saltpeter). The sulfur and charcoal act as fuels, and the saltpeter is an oxidizer. Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks. Formulations used in blasting rock (such as in quarrying) are called blasting powder. Gunpowder is mainly used in older guns now because the propellants used today are too powerful and could break the already fragile barrels.