railgun

A railgun is an electro-magnetic projectile launcher typically consists of two or more metal rails flanking the launcher (hence the name) connected to an electrical power supply. When a conductive projectile is inserted between the rails (at the end connected to the power supply), it completes the circuit, launching a projectile with extreme force and speed.

As of current, real life railgun is still under development to reduce the power input needed to operate the system, and to reduce the wearing of the system for military uses. Railguns are often seen in science fiction works due to their advanced design and extreme power.

Not to be confused with Railway gun. For a manga and anime spin-off of Toaru Majutsu no Index, see Toaru Kagaku no Railgun, or Railgun (Misaka Mikoto) for the specific attack done by the main character of the series.