The aerial bombing of cities is an optional element of strategic bombing, which became widespread in warfare during World War I. The bombing of cities grew to a vast scale in World War II and is still practiced today. The development of aerial bombardment marked an increased capacity of armed forces to deliver ordnance from the air against combatants, military bases, and factories, with a greatly reduced risk to its ground forces. The killing of civilians and non-combatants in bombed cities has variously been a deliberate goal of strategic bombing, or unavoidable collateral damage resulting from intent and technology. A number of multilateral efforts have been made to restrict the use of aerial bombardment so as to protect non-combatants and other civilians.

Strategic bombing is a systematically organized and executed attack from the air which can utilize strategic bombers, long- or medium-range missiles, or nuclear-armed fighter-bomber aircraft to attack targets deemed vital to the enemy's war-making capability. It is a military strategy used in total war with the goal of defeating the enemy by destroying its morale, its economic ability to produce and transport materiel to the theatres of military operations, or both. The term terror bombing is used to describe the strategic bombing of civilian targets without military value, in the hope of damaging an enemy's morale.