A light source, a light source assembly, a display device and a display method. The light source comprises a first light emitting region and a second light emitting region. The first light emitting region and the second light emitting region can control ON or OFF of the light emission separately. The first light emitting region and the second light emitting region are arranged alternately along a first direction. The first light emitting region and the second light emitting region of the light sources in this disclosure can be controlled separately. Hence, one light emitting region can be made to emit light while the other light emitting region can be made to be turned off. There is no stray light in the turned-off light emitting region, so as to avoid stray light crosstalk to light of the other light emitting region.