These are powerful energy beams that travel through air or space in straight lines. They travel at the speed of light and can strike over distances of thousands of kilometres.
How they work: Large mirrors focus powerful laser beams onto a small spot on the target. The heat produced burns through the surface of the target, disrupting flight, disabling warheads, or igniting fuels or explosives.
Limitations: It needs much more energy to do damage than bullets, which destroy targets with their momentum. Powerful lasers need fuel or electrical power and are also very bulky (the US Airborne Laser fills a Boeing 747). Travelling through air and turbulence can disperse the energy of the beam.