A lithographic apparatus comprising a first component and a second component that are configured to undergo relative movement with respect to one another in one of a scanning direction and a stepping direction substantially perpendicular to the scanning direction, wherein: the first component has a first surface; the second component has a second surface; wherein the first surface and the second surface face each other; at least a specific one of the first surface and the second surface accommodates a barrier system; and the barrier system is configured to provide a barrier operative to reduce or prevent an inflow of ambient gas into a protected volume of gas between the first surface and the second surface; and the barrier system comprises at least one of: a wall (200, 290) enclosing part of the protected volume adjacent the specific one of the first surface and second surface; and at least one opening (110, 120) adapted for a flow of barrier gas therefrom for establishing a gas curtain enclosing part of the protected volume adjacent the specific one of the first surface and second surface, wherein the at least one opening (110, 120) comprises an inner opening configured to provide a turbulent flow of barrier gas and the at least one opening comprises an outer opening configured to provide a laminar flow of barrier gas adjacent to the turbulent flow of barrier gas from the inner opening; the barrier has a geometry in a plane in which the scanning direction and the stepping direction lie, and the barrier is operative to guide a flow of ambient gas around the protected volume, the flow of ambient gas being induced by the relative movement of the first component and the second component; the geometry has a first corner and a second corner; the first corner serves as a leading edge of the barrier and the second corner serves as a trailing edge of the barrier when the first component and the second component move relative to one another in a specific one of the scanning direction and the stepping direction; and the first corner serves as the trailing edge of the barrier and the second corner serves as the leading edge of the barrier when the first component and the second component move relative to one another in a further direction opposite to the specific direction. the first component has a first surface; the second component has a second surface; wherein the first surface and the second surface face each other; at least a specific one of the first surface and the second surface accommodates a barrier system; and the barrier system is configured to provide a barrier operative to reduce or prevent an inflow of ambient gas into a protected volume of gas between the first surface and the second surface; and the barrier system comprises at least one of: a wall (200, 290) enclosing part of the protected volume adjacent the specific one of the first surface and second surface; and at least one opening (110, 120) adapted for a flow of barrier gas therefrom for establishing a gas curtain enclosing part of the protected volume adjacent the specific one of the first surface and second surface, wherein the at least one opening (110, 120) comprises an inner opening configured to provide a turbulent flow of barrier gas and the at least one opening comprises an outer opening configured to provide a laminar flow of barrier gas adjacent to the turbulent flow of barrier gas from the inner opening; the barrier has a geometry in a plane in which the scanning direction and the stepping direction lie, and the barrier is operative to guide a flow of ambient gas around the protected volume, the flow of ambient gas being induced by the relative movement of the first component and the second component; the geometry has a first corner and a second corner; the first corner serves as a leading edge of the barrier and the second corner serves as a trailing edge of the barrier when the first component and the second component move relative to one another in a specific one of the scanning direction and the stepping direction; and the first corner serves as the trailing edge of the barrier and the second corner serves as the leading edge of the barrier when the first component and the second component move relative to one another in a further direction opposite to the specific direction.