Explosives can be categorized by their performance and reaction speed as low explosives, high explosives, or blasting agents. Low explosives have a low reaction speed. Examples of such explosives are black powder, smokeless powder, and other materials referred to as pyrotechnics. Pyrotechnics are a combination of various fuel and oxidizer mixtures used to produce a variety of visual and sound effects through the burning process. Low explosive materials, such as black and smokeless powder, along with pyrotechnics, account for a large portion of the explosive filler found in improvised explosive devices in the United States and abroad. Individual criminals, criminal organizations, and terrorists have easy access to the materials used in improvised explosive devices. High explosives are categorized as either primary or secondary explosives. Primary explosives are sensitive high explosives used to stimulate the chemical reaction of a less-sensitive secondary explosive. These primary explosives are often called blasting caps or detonators. When activated, the blasting cap or detonator starts the initial detonation process within the secondary high explosive. This chapter describes types of commercial high explosives (dynamite and detonation cord), a blasting agent (ANFO), four types of grenades, and improvised explosive devices (pipe bombs and vehicle-borne improvised explosive devices). The types of improvised explosive devices typically used by suicide/homicide bombers are also described.