China has reopened its borders to travellers from abroad for the first time in nearly three years.
People will no longer have to quarantine on arrival but a negative COVID test - taken within the last 48 hours - will still need to be shown.
The change has led to long queues at Hong Kong airport as people take the chance to finally travel to the mainland - many of them for long-overdue reunions with family.
"I'm so happy, so happy, so excited. I haven't seen my parents for many years," said Teresa Chow at a China-Hong Kong border checkpoint on Sunday.
Some 300,000 bookings from Hong Kong to mainland China have already been made, according to media in the city.
However, it could take a while until the number of international flights gets close to pre-pandemic levels.
Beijing's Capital airport was expecting just eight flights from overseas on Sunday. Shanghai had its first international flight at 6.30 am, with just a few more expected.
China has also resumed issuing passports and travel visas.
With foreign travel off the table since 2020, travel companies have reported a big increase in inquiries about holiday destinations near China, such as Indonesia and Thailand.
Sunday's border change is a significant moment after China cut itself off from the rest of the world as it enforced its zero-COVID strategy.
Read more: Zero-COVID absolutely hammered China
The government finally rowed back from that after its citizens grew increasingly exasperated and took to the streets at the end of 2022 in some of the biggest protests for years.
However, coronavirus infections in China have surged as a result, with hospitals said to be inundated with patients.
Many Western countries, including the UK, have responded in recent weeks by imposing fresh rules on arrivals from China, such as the need to show a negative test before flying.
Governments and the World Health Organisation are concerned that China is concealing the extent of its surge in deaths and infections - something it denies.
The reopening of borders also coincides with the start of New Year travel, during which people traditionally return to their hometown to see family.
Two billion trips are expected to be made this season, 70% of pre-COVID levels, the government said.