Chinese police categorise prostitution practices according to a descending hierarchy of seven tiers, though this typology does not exhaust the forms of practices that exist. These tiers highlight the heterogeneous nature of prostitution and prostitutes. While they are all classified as prostitutes, the services they offer can be very different. Within some tiers, for example, there is still some revulsion to the acts of anal sex and oral sex. In parallel with the wide range of backgrounds for prostitutes, male buyers of sex also come from a wide range of occupational backgrounds. According to the local police, in China there are seven categories of prostitutes: