Light pollution is excessive or obtrusive artificial light that has negative impacts. It is most severe in highly populated urban areas. There are several types of light pollution including light trespass, over-illumination, glare, and sky glow. Light pollution disrupts ecosystems and human health, increasing risks like cancer, stress, and sleep deprivation. It also wastes energy and interferes with astronomy. Reduction methods include using minimum light intensities, timers, improved fixtures, and full-cutoff lights to prevent sky glow. Light pollution is a growing global problem.