A lithographic apparatus including a barrier system and a device manufacturing method using such a lithographic apparatus. The barrier system is used to maintain a protected volume of gas within a barrier. The protected volume may be maintained when different components of the lithographic apparatus move relative to each other. The barrier system may be used in different locations within the lithographic apparatus. The geometry of the barrier affects how efficiently the protected volume is maintained, especially at high speeds. The geometry reduces the amount of ambient gas entering the protected volume from outside the barrier.