A firearm is a weapon that launches one or more 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, 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.