Millions of Chinese expats reportedly use VPNs to get inside the "Great Firewall".

For most of those outside China's Great Firewall, the idea of life without Facebook, Instagram and Twitter has become difficult to imagine.

Key points:

• Chinese people who move overseas are unable to access all content from home
• A digital firewall not only blocks Western content in China, but also works in the reverse
• Experts say the divided internet creates a disconnect for Chinese people living abroad

But many Chinese people find that when they go overseas and leave the Firewall behind, that's exactly what they crave: a return to the heavily censored content they're accustomed to consuming online.

And just as their compatriots back home use VPNs to scale President Xi Jinping's digital fortress and use Western social media platforms, millions of Chinese expats overseas reportedly use VPNs to get back inside it.

Linda Yang uses a VPN to access digital content from inside China.

Among them is 24-year-old Linda Yang, a student at the University of Melbourne who realised when she arrived in Australia a year ago that a whole catalogue of songs in her Chinese music app were no longer available.

With the help of some international classmates, she discovered a VPN that specialises in helping Chinese people overseas avoid restrictions on some Chinese websites — a service she still uses regularly.

"Frankly I was amazed the first time, because I had only heard of people in China jumping outside the Firewall, but I never thought there was such a service specially for jumping back in," Ms Yang told the ABC.

There are several VPN services commonly used by the overseas Chinese community for this purpose.

'Loneliness of living overseas'

Among the three most popular is Transocks, which told the ABC it has almost 10 million devices connected worldwide — mostly international students and Chinese people living abroad — since it was set up just over two years ago.

A spokesperson said it was originally conceived because members of the China-based team "have many friends abroad who spoke about the loneliness of living overseas, and strongly expressed their wish to use all kinds of Chinese music and video apps like they did in China".

Jumping China's Great Firewall

China has the world's most sophisticated online censorship operation, but Chinese entrepreneur Zou Chengfeng says he managed to train tens of thousands to jump over the firewall.

In 2014, Chinese President Xi Jinping launched the country's National Cyber Development Strategy, urging both government and private enterprise to speed up the construction of China's digital infrastructure and promote the development of its internet culture.

Since then, China has experienced a digital boom, with mobile apps such as WeChat and Alipay becoming deeply integrated into the lives of many netizens.

Many of China's youth have never known life with Facebook or Google.

At the same time, the Chinese Government has continued to upgrade the Great Firewall — a digital border first built to control its citizens' access to the internet in the mid-1990s — by blocking more websites and cracking down on people using VPNs to access blocked content.

Young Chinese netizens have gradually warmed to local substitutes for globally popular apps and platforms that are not accessible in China, developing user behaviour distinct to the country.

Ms Yang said that her desire to jump inside the Firewall was a continuation of the internet usage patterns she had before going overseas.

"I didn't intentionally want to maintain my habits. I felt like it … because I like [content from China] and the VPN is easy to use," she said.

Behaviour 'shaped by authorities'

Liu Yiming, an independent commentator on Chinese culture, said Ms Yang's internet usage was in line with one of China's digital goals — to increase its citizens' dependence on platforms inside the Firewall while suppressing interest in blocked platforms.

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"Many people struggle to change their lifestyle and internet habits [overseas] because they lived in China for a long time," he told the ABC.

Mr Liu said many Chinese internet users were beset by a kind of Stockholm syndrome.

"Both their thinking and behaviour modes are shaped by authorities, while many of them are sharing the same collective unconsciousness," he said.

Mr Liu said this often created a disconnect between Chinese people living overseas — accustomed to an orderly, censored digital experience — and the chaotic, free internet of the open societies they have migrated to.

The dual function of the Great Firewall, he argued, demonstrates how Beijing struggles to compete with the West in terms of soft power.

"It shows a lack of confidence to block people [in China] from reading foreign media, and it is also lack of confidence to block people from accessing domestic information from overseas," Mr Liu said.

Amnesty volunteers place cardboard bricks into a symbolic firewall during a protest in Sydney.