Example for comparison: visadb for US->China only says "Visa required to travel".
The expertflyer pull goes into detail about the extended visa-free "transits", exceptions for some visa-on-arrival tourist programs, requirements for also entering Tibet, requirements for yellow fever vaccination, requirements for children traveling with an adult, etc.
 While many non-US countries have the concept of visa-free transit for connecting from one international flight to another, they usually require you remain in the airport the entire time. In certain cities, China allows you to leave the airport, stay in a hotel and see the city for 3-6 days depending on which city you "transit" in, so long as the origin of your immediate inbound flight and destination of your immediate outbound flight are not the same country. Some airlines infamously have trouble with this, since their agents incorrectly enter a destination of China (due to a planned multi-day stay) instead of a transit of China, and get back a result requiring a visa.
Most recently, I've seen AA passengers complain due to the popularity of a mileage run LAX-PEK-NRT-LAX, where the passenger spends a couple days in Beijing and never leaves the airport in Tokyo. From the perspective of the Chinese policy, this is a valid round trip to Tokyo with an outbound connection in Beijing, requiring no visa for the transit of China. AA agents try to enter as a round trip to Beijing with a return connection in Tokyo, requiring a visa to visit China.