Red-light districts are areas in cities or towns that are themed around sex. They consist of clusters of activities or individuals and can be widely known outside the immediate area. The definition of red-light district has varied by place and time. They may be characterized by prostitution alone, but some districts have few or no visible prostitutes and consist of entertainment or other services. They can be characterized by entertainment of a sexual nature or by ancillary services related to sex, including the sale of books and videos, sexual aids, and clothing of a sexual nature.

The origin of the term is uncertain, but even today, districts in some cities, such as Amsterdam, are characterized by red lights in shop windows occupied by prostitutes, which are ...