A red-light district is a part of an urban area where sex work is concentrated. Sex work in red-light districts is either legal or illegal, but tolerated. In the world there are many red-light districts, the most famous probably being the red-light district in Amsterdam, De Wallen. In the red-light district, sex workers are often helped and protected, and every month doctors visit them. Condoms are given to the sex worker so they do not catch any sexually transmitted diseases (STD's). In some red-light districts, sex workers pay taxes, as in the red-light district of Amsterdam. In other red light districts, sex workers do not pay taxes, because there they are illegal and often are put on the street with violence. In some parts of Africa there are villages of sex workers where they live and work, because they are not accepted by the people of other villages.