Bomber CommandBomber Command is an organizational military unit, generally subordinate to the air force of a country. Many countries have a "Bomber Command", although the most famous ones were in the United States and Britain. A bomber command is generally composed of bombers (i.e. planes used to bomb targets).
The British Bomber Command was most famous during World War II, when its many bombers were used to attack various targets, mostly in France and Germany. The most used planes were Avro Lancasters, although other planes (even American planes, such as the B-17) were used.
The American Bomber Command was less famous, mainly because it was used less often (mainly in the Pacific War). Detachments were generally used to soften targets before marine or army invasions of the enemy islands held by Japanese forces. Generally, in this case, the term "bomber command" is used mainly substituting the term "headquarters".