Smart bombs are explosive weapons that are precision-guided for enhanced accuracy. Radar, laser, infrared and satellite guidance systems are used to guide smart bombs to their targets. Signals sent by these guidance systems to a built-in computer on the bomb cause the bomb to adjust its fins, altering its course.
As smart bombs have become more common in modern warfare, civilian casualties have dropped significantly. In World War II, large-scale bombing of cities using unguided bombs led to many civilian deaths and nearly destroyed entire cities. With the use of smart bombs in the 2003 U.S. invasion of Iraq, the initial bombing campaign led to civilian casualties numbering in the hundreds, a figure that is relatively low compared to earlier wars.