Simplify the following text for a Grade 9 native English-speaking person.
Original: The most well known red-light district is probably De Wallen in Amsterdam , Netherlands . The countries most often associated with red-light districts and prostitution are Netherlands and Thailand , but there are areas in many big cities around the world which have acquired international reputation as red-light districts , though usually without official recognition and often with official disapproval .
Simplified: In the world there are many red-light districts , the most famous probably being the red-light district in Amsterdam .