Light is imperative to achieve viable conditionsfor human activity at night. However, for the lighting to besustainable, it is crucial to reduce unwanted and harmful sideeffectsof light at night (LAN). These unwanted effects andimpacts are often referred to as light pollution. Hitherto, it hasbeen somewhat unclear how all these adverse effects can bedescribed in a systematic way and whether light pollution issimilarly defined among different scientific disciplines andcontexts. Therefore, in this review, we present an overview ofthe identified areas where light pollution can be confirmed fromthe scientific literature and the methods commonly used withinthese areas. We have identified three key areas: astronomicallight pollution (ALP), ecological light pollution (ELP), andimpacts of LAN on humans in two subareas; impacts on humanhealth (physiology and behaviour) and impacts on humans interms of obtrusive light that can be perceived as negative, forexample, discomfort, annoyance, nuisance and distractions.Methods used in various disciplines are partly similar, e.g.,satellite-based sensor collected data are used in all three areasto study impacts, but specific methods are also used within eachfield.