Window, which has at least the following features: a) a window frame composed of a plurality of frame profiles, b) a sash frame composed of a plurality of frame profiles, which sash frame has at least one surface element and is movable relative to the window frame at least between a closed position and a ventilation position, c) wherein a frame rebate space is formed between the frame profiles (1', 2') of the window frame and the frame profiles (1', 2') of the sash frame, d) at least one ventilation duct formed in at least one of the frame profiles of the window frame or in at least one of the frame profiles of the sash frame, which ventilation duct has a first ventilation duct opening and a second ventilation duct opening, e) wherein the sash frame and the window frame are designed to close at least one of the ventilation duct openings (9, 10) in the closed position, and to open both ventilation duct openings (9, 10) of the at least one ventilation duct in the ventilation position, f) wherein at least one sealing plane is formed between the window frame and the sash frame in the region of the frame rebate space in the open state, more precisely in the ventilation position, which sealing plane is formed by at least one seal (18, 104, 105), which, at least in the ventilation position, rests against the window frame or against the sash frame, and which is formed as a center and abutment seal which has a sealing base and at least one sealing section which is pivotably fastened to the sealing base, is connected in an articulated manner to the sealing base and, at any rate in the region or regions in which a respective ventilation duct is formed, rests at its free end with an abutment sliding section against the sash frame or against the window frame, characterized in that g) the sealing section has at least one joint or a plurality of joints, so that the sealing section is in turn divided into at least two sub-sections. a) a window frame composed of a plurality of frame profiles, b) a sash frame composed of a plurality of frame profiles, which sash frame has at least one surface element and is movable relative to the window frame at least between a closed position and a ventilation position, c) wherein a frame rebate space is formed between the frame profiles (1', 2') of the window frame and the frame profiles (1', 2') of the sash frame, d) at least one ventilation duct formed in at least one of the frame profiles of the window frame or in at least one of the frame profiles of the sash frame, which ventilation duct has a first ventilation duct opening and a second ventilation duct opening, e) wherein the sash frame and the window frame are designed to close at least one of the ventilation duct openings (9, 10) in the closed position, and to open both ventilation duct openings (9, 10) of the at least one ventilation duct in the ventilation position, f) wherein at least one sealing plane is formed between the window frame and the sash frame in the region of the frame rebate space in the open state, more precisely in the ventilation position, which sealing plane is formed by at least one seal (18, 104, 105), which, at least in the ventilation position, rests against the window frame or against the sash frame, and which is formed as a center and abutment seal which has a sealing base and at least one sealing section which is pivotably fastened to the sealing base, is connected in an articulated manner to the sealing base and, at any rate in the region or regions in which a respective ventilation duct is formed, rests at its free end with an abutment sliding section against the sash frame or against the window frame, characterized in that g) the sealing section has at least one joint or a plurality of joints, so that the sealing section is in turn divided into at least two sub-sections.