A bomber is a military combat aircraft designed to attack ground and naval targets by dropping air-to-ground weaponry (such as bombs), launching torpedoes, or deploying air-launched cruise missiles. The first use of bombs dropped from an aircraft occurred in the Italo-Turkish War, with the first major deployments coming in the First World War and Second World War by all major airforces causing devastating damage to cities, towns, and rural areas. The first purpose built bombers were the Italian Caproni Ca 30 and British Bristol T.B.8, both of 1913. Some bombers were decorated with nose art or victory markings.

There are two major classifications of bomber: strategic and tactical. Strategic bombing is done by heavy bombers primarily designed for long-range bombing missions against strategic targets to diminish the enemy's ability to wage war by limiting access to resources through crippling infrastructure or reducing industrial output. Tactical bombing is aimed at countering enemy military activity and in supporting offensive operations, and is typically assigned to smaller aircraft operating at shorter ranges, typically near the troops on the ground or against enemy shipping.

During WWII with engine power as a major limitation, combined with the desire for accuracy and other operational factors, bomber designs tended to be tailored to specific roles. Early in the Cold War however, bombers were the only means of carrying nuclear weapons to enemy targets, and held the role of deterrence. With the advent of guided air-to-air missiles, bombers needed to avoid interception. High-speed and high-altitude flying became a means of evading detection and attack. With the advent of ICBMs the role of the bomber was brought to a more tactical focus in close air support roles, and a focus on stealth technology for strategic bombers.