The present disclosure provides a light bulb for use in a lamp housing of a vehicle. The light bulb includes a bulb body assembly having one or more light sources fixedly attached thereto, and a mounting assembly configured to mount on the lamp housing. The bulb body assembly and the mounting assembly are connected by a rotatable joint such that positions of the one or more light sources can be adjusted after the mounting assembly is mounted on the lamp housing. In some embodiments, a key portion is attached to the bulb body assembly to rotate the bulb body assembly relative to the mounting assembly.