The main distinguishing feature of an Improvised Explosive Device, commonly called an IED, is its makeshift or homemade quality; IED builders use materials at hand, and a variety of techniques, to create explosives designed to be lethal. They may use explosives alone, or combine explosives with radiological, chemical or biological materials. The explosives may homemade, commercial or military grade. IEDs are composed of :
- an initiation system that sets off the explosive;
- explosive material;
- a detonator;
- a container or means of conveyance.
IEDs may be detonated in one of several ways, depending on their design and intended target. Those that use concealed mortar and artillery projectiles can be thrown into or placed in a designated area, often concealed. Vehicle Borne IEDs (VBIEDs) use cars or trucks to contain the explosive device. Suicide bomb IEDs make use of the human body to convey the IED.
The Vietcong made use of IEDs during the Vietnam War. Other militias and terrorist groups including Chechen rebels, Hezbollah, the IRA, and Iraq insurgents have used IEDs in attacks. In October 2006, the U.S. military reported that the number of IEDs in Iraq was higher than at any previous point.