A gun is a ranged weapon designed to use a shooting tube (gun barrel) to launch typically solid projectiles, but can also project pressurized liquid (e.g. water guns/cannons, spray guns for painting or pressure washing, projected water disruptors, and technically also flamethrowers), gas (e.g. light-gas gun) or even charged particles (e.g. plasma gun). Solid projectiles may be free-flying (as with bullets and artillery shells) or tethered (as with Taser guns, spearguns, and harpoon guns). A large-caliber gun is also referred to as a cannon.

Shooting is the act or process of discharging a projectile from a ranged weapon (such as a gun, bow, crossbow, slingshot, or blowpipe). Even the acts of launching flame, artillery, darts, harpoons, grenades, rockets, and guided missiles can be considered acts of shooting. When using a firearm, the act of shooting is often called firing as it involves initiating combustion (deflagration) of chemical propellants.

Science fiction (sometimes shortened to sci-fi or SF) is a genre of speculative fiction that typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel universes, and extraterrestrial life. It has been called the literature of ideas, and often explores the potential consequences of scientific, social, and technological innovations.