A gravity bomb is a munition designed to be dropped from aircraft. It may or may not maneuver itself; however, the characteristic that identifies it as such is that it does not provide its own motive force for travel. The only force acting on the munition that provides acceleration is gravity. Maneuvering with passive control surfaces is sometimes accomplished by targeting or navigation systems onboard. See General Purpose Bombs for examples of gravity bombs, or see JDAM or Competent Munition for examples of smarter weapons.