An afterburner is an additional component typically found on military jet engines. It is a device that introduces additional fuel into the jets exhaust stream just to the rear of the last turbine, significantly increasing thrust but using large amounts of fuel to do so; therefore, it's not very fuel-efficient. Usually used for takeoffs, combat, and to achieve supersonic flight. Dry means no afterburner use; wet means fuel is added to the exhaust stream to get the additional thrust.