Optimizing the perception of exteal cues and regulating physiology accordingly help plants to cope with the constantly changing environmental conditions to which they are exposed.An array of photoreceptors and intricate signaling pathways allow plants to convey the surrounding light information and synchronize an endogenous timekeeping system known as the circadian clock.This biological clock integrates multiple cues to modulate a myriad of downstream responses,timing them to occur at the best moment of the day and the year.Notably,the mechanism underlying entrainment of the light-mediated clock is not clear.This review addresses known interactions between the light-signaling and circadian-clock networks,focusing on the role of light in clock entrainment and known molecular players in this process.