Abstract: A lamp includes at least two illumination parts and a lamp body. The lamp body has an upper portion, a lower portion corresponding to the upper portion and at least two optical cavities extended between the upper portion and the lower portion. The illumination parts are respectively arranged in the optical cavities. The lamp has a surrounding lighting state and a side lighting state. The lighting states of the lamp may be switched between the surrounding lighting state and the side lighting state through controlling the operating modes of the illumination parts in the optical cavities respectively.