A firearm is a weapon that launches one, or many, projectile(s) at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically black powder or cordite, but modern firearms use smokeless powder or other propellants. Most modern firearms (with the notable exception of smoothbore firearms) have rifled barrels to impart spin to the projectile for improved flight stability.
As a survival tool, the gun has countless uses. Everything from food acquisition to personal protection and in between. Every survivalist should at least have basic marksmanship training, even if only with a small caliber gun.