||Artificial lighting is both a precondition and a consequence of the 24-hour society. It makes public spaces safer, allows a range of economic and social activities at night and influences the way goods production and services, buildings and entire cities are organised. Despite these achievements, from early on, critical voices have drawn attention to the negative impact of artificial lighting on humans, animals, cityscapes, landscapes and energy consumption. This has recently culminated in growing criticism of âlight pollutionâ. This chapter investigates from a socioeconomic perspective the economic and social functions of artificial light, on the one hand, and the âloss of the nightâ, on the other, and outlines a preliminary taxonomy of relevant positive and negative effects of nocturnal artificial light. It is part of a joint research project on the âloss of the nightâ, which aims to develop new concepts of lighting to reduce light pollution.