The rule in one paragraph
China’s 240-hour visa-free transit allows eligible passport holders to enter through selected ports and travel within a designated region for up to ten days. It is a transit policy, not a tourist visa: you must be travelling to a third country, and your onward ticket must leave from a port that is part of the scheme.
Who actually qualifies
The list changes. Check the current official list before booking, and check it again the week you fly. Your passport must usually have at least six months’ validity, and you need a confirmed onward ticket. Hong Kong and Macau count as third regions for many itineraries, but the rules depend on your nationality and the port.
Which ports work
Major international airports and some cruise and land ports participate. The permitted travel area depends on the port of entry: Shanghai and the Yangtze Delta, Beijing and the Jing-Jin-Ji region, Chengdu and nearby cities, and others each have their own boundaries. Do not assume a ticket into Shanghai lets you fly out of Beijing; check the pairing first.
The mistake that costs you
The expensive mistake is booking a return ticket to the same country you arrived from. The transit rule requires a third destination. The second mistake is arriving at a port that is not in the scheme. The third is not having the onward ticket ready at the immigration desk. Print it, and save it offline.