Valve, in particular for opening and closing exhaust-gas lines, having - a housing, - a plunger which is arranged in the housing and which can be coupled to a drive and which is designed to be moved by means of the drive along a longitudinal axis of the plunger, - a recess which is formed in the housing, - a valve seat which is arranged in the recess of the housing and which delimits a valve opening, - a further valve opening which is delimited by the recess formed in the housing, and - a valve body which is fixedly connected to the plunger, wherein the valve body is designed in such a way -- that the valve body can, by way of a movement of the plunger, be actuated between an open position, in which the valve opening is opened up, and a closed position, and -- that, in the closed position, the valve body bears in each case sealingly against the valve seat so as to close off the valve opening and against the housing so as to close off the further valve opening, wherein the valve body has a first contact region, which in the closed position bears against the valve seat so as to form a first seal, and a second contact region, which in the closed position bears against the housing so as to form a second seal, wherein - the valve body is of disc- or plate-like form and is arranged around the plunger; - the valve body is of stepped form on a side facing towards the valve openings (12, 17), wherein each step forms a contact region (21, 24); - the valve seat is mounted so as to be displaceable relative to the plunger with respect to the longitudinal axis of the plunger; characterized in that - the valve seat has a projection which runs around in a radial direction with respect to the longitudinal axis and which engages into a groove formed in the housing, wherein the groove is designed to limit the displaceability of the valve seat between two end positions; - a spring element is arranged in the recess between the valve seat and a shoulder, situated opposite the further valve opening, of the housing and is designed in such a way that the spring element exerts a force on the valve seat in the direction of the valve body. - a housing, - a plunger which is arranged in the housing and which can be coupled to a drive and which is designed to be moved by means of the drive along a longitudinal axis of the plunger, - a recess which is formed in the housing, - a valve seat which is arranged in the recess of the housing and which delimits a valve opening, - a further valve opening which is delimited by the recess formed in the housing, and - a valve body which is fixedly connected to the plunger, wherein the valve body is designed in such a way -- that the valve body can, by way of a movement of the plunger, be actuated between an open position, in which the valve opening is opened up, and a closed position, and -- that, in the closed position, the valve body bears in each case sealingly against the valve seat so as to close off the valve opening and against the housing so as to close off the further valve opening, wherein the valve body has a first contact region, which in the closed position bears against the valve seat so as to form a first seal, and a second contact region, which in the closed position bears against the housing so as to form a second seal, wherein -- that the valve body can, by way of a movement of the plunger, be actuated between an open position, in which the valve opening is opened up, and a closed position, and -- that, in the closed position, the valve body bears in each case sealingly against the valve seat so as to close off the valve opening and against the housing so as to close off the further valve opening, wherein the valve body has a first contact region, which in the closed position bears against the valve seat so as to form a first seal, and a second contact region, which in the closed position bears against the housing so as to form a second seal, - the valve body is of disc- or plate-like form and is arranged around the plunger; - the valve body is of stepped form on a side facing towards the valve openings (12, 17), wherein each step forms a contact region (21, 24); - the valve seat is mounted so as to be displaceable relative to the plunger with respect to the longitudinal axis of the plunger; characterized in that - the valve seat has a projection which runs around in a radial direction with respect to the longitudinal axis and which engages into a groove formed in the housing, wherein the groove is designed to limit the displaceability of the valve seat between two end positions; - a spring element is arranged in the recess between the valve seat and a shoulder, situated opposite the further valve opening, of the housing and is designed in such a way that the spring element exerts a force on the valve seat in the direction of the valve body.