How is thrust produced in a jet engine?

Thrust in a jet engine is produced by accelerating air through the engine according to Newton's third law. The momentum equation shows: Thrust = (mass flow x exit velocity) - (mass flow x inlet velocity) + pressure thrust. In turbofans, thrust comes from both the high-velocity core exhaust and the larger mass flow of lower-velocity bypass air. Increasing mass flow (larger fan) or exit velocity (higher temperatures, better expansion) increases thrust. The nozzle converts pressure to velocity for final acceleration. Afterburners add fuel to the exhaust for significant thrust increase at the cost of high fuel consumption.