Rail, rail structure, seat assembly and vehicle

The utility model relates to a rail, a rail structure, a seat assembly and a vehicle, the rail is suitable for being used as a first rail of the rail structure, a containing cavity with an opening is formed in the rail, the rail is further provided with a stopping face, and the stopping face is used for stopping a first rolling body of the rail structure. The first rolling body is arranged in the containing cavity and close to one side of the opening, the stopping face is constructed to be capable of making contact with the first rolling body, the stopping face is at least provided with a first point used for making contact with the first rolling body, the first point is suitable for being arranged on one side, close to the opening, relative to a second point, and the second point is the highest point of the first rolling body. The height of the first point is adapted to be lower than the height of the second point. When the track is used as the first track of the track structure, the stop surface can change