An improvised explosive device (IED) is a bomb constructed and deployed in ways other than in conventional military action. It may be constructed of conventional military explosives, such as an artillery shell, attached to a detonating mechanism. IEDs are commonly used as roadside bombs.
IEDs are generally seen in heavy terrorist actions or in asymmetric unconventional warfare by insurgent guerrillas or commando forces in a theatre of operations. In the second Iraq War, IEDs were used extensively against US-led invasion forces and by the end of 2007 they had become responsible for approximately 63% of coalition deaths in Iraq. They are also used in Afghanistan by insurgent groups, and have caused over 66% of coalition casualties in the 2001–present Afghanistan War.
IEDs were also used extensively by cadres of the rebel Tamil Tiger (LTTE) organization against military targets in Sri Lanka.