Hong Kong (CNN) At work in central Hong Kong, David Hand is surrounded by people speaking Chinese and English. But inside his home, the Welsh language rules.

Hand's three children -- Arwen, Huw and Tomos -- have never lived in Wales, spending their entire lives in Asia.

Inculcating his native language in them thousands of kilometers from the only place it is widely spoken wasn't easy. As well as only speaking to them in Welsh himself, Hand hired nannies from Wales -- usually teenagers taking time out between high school and university -- and arranged for them live to with the family.

Their Australian mother speaks to them in English.

"As the kids were growing up until the age of five we always had a Welsh speaker at home in addition to me," Hand said.

"It's about the mindset of thinking of yourself as Welsh and a Welsh speaker, and compare yourself to a French person or a Spaniard or a German. They wouldn't contemplate not teaching their children their own language."

Despite this, Hand's family is something of a rarity. Many Welsh speakers see their language skills diminish after they leave the country and switch to primarily speaking English or another language.

There also aren't the international schools and other institutions available to French, German or Japanese who want their children to grow up speaking a particular language.

Nor is the fact that the Hand children speak Welsh remarkable just due to where they live. Only a generation ago, the language was on the verge of dying out completely, joining the hundreds of other languages which have gone extinct in the last half century.

Today it is spoken by about half a million people in Wales, or just under 19% of the population -- a rate which has remained stable for almost a decade.

The story of the Welsh revival is one of tremendous organizing and effort by activists and politicians, who not only saved their own tongue but also established a blueprint of sorts which can be used by other languages under threat, including Hong Kong's own Cantonese.

Such a blueprint is desperately needed. Languages are far more vulnerable than many people realize, and can die out in a single generation if not passed down from parent to child.

This year is the United Nations International Year of Indigenous Languages , an event designed to raise awareness of the more than 1,700 languages listed as endangered by UNESCO.

More and more languages die out every year. And even as digital tools and communities help in the fight against the decline, some experts warn changes in how we communicate online could drastically accelerate language extinction.

Listen to an introduction to Welsh in that language.

Language under threat (Iaith dan fygythiad)

"The Welsh language is a vast drawback to Wales, and a manifold barrier to the moral progress and commercial prosperity of the people."

So concluded an 1847 report prepared for the UK government in the wake of widespread social unrest in Wales which much of the English press blamed on the "lack of education of the Welsh people."

"It is not easy to overestimate its evil effects," the report said of the country's native language, adding "there is no Welsh literature worthy of the name."

In the wake of the report, Welsh Nots , planks of heavy wood that were hung around students' necks if they were caught speaking Welsh in school, became a common sight across the country. As one teacher wrote in his school's log book in 1870: "Endeavored to compel the children to converse in English by means of a piece of wood. Offenders to be shut in after school hours."

These attitudes, along with increased immigration to England, helped lead to a staggering drop in the use of Welsh. By the time Plaid Cymru -- the Party of Wales -- was founded in 1925, the number of Welsh speakers had fallen to 37% of the population and appeared headed into terminal decline.

Growing up in west Wales in the 1950s and '60s, Toni Schiavone was constantly aware of the language's second-class status in the eyes of the English-speaking elite which governed the country.

"Our culture was being slowly destroyed," he said. "Although I was born and grew up in a Welsh-speaking area, my education was 95% in the medium of English, everything around us was in English. It was being predicted that there would be no Welsh speakers by the turn of the century."

Schiavone was an early member of Cymdeithas yr Iaith Gymraeg -- the Welsh Language Society -- which organized to protect the country's native tongue via demonstrations and non-violent direct action. Members of Cymdeithas vandalized English-only road signs, staged sit-ins and protests, and campaigned for the establishment of a Welsh-language public television station, which was finally launched in 1982 as S4C.

This took no small amount of commitment to the cause. "In the 1970s people went to jail because road signs weren't available in Welsh, or because they refused to pay the TV license because we didn't have a Welsh language TV channel," Schiavone said.

Thanks to pressure from groups like Cymdeithas and the growing electoral success of Plaid Cymru, the political winds began to turn in favor of Welsh. In 1993 a law was passed to permit the language's use in court and put it on an equal footing with English for all public services. In decades since, Welsh education has been ramped up nationwide and in 2011 it became the country's official language.

The reversal in attitudes came not a moment too soon. At the 1991 census, only 18.5% of the population spoke Welsh, an all-time low. A decade later, however, that figure was more than 20% -- and the language's decline appears to have halted since, stabilizing at about a fifth of the population despite continued immigration from England and other countries.

The government of Wales -- which won partial autonomy from the UK in 1997 -- is now thoroughly invested in promoting the Welsh language, setting a target of one million Welsh speakers by 2050, for an estimated population of around 3.5 million.

"We've turned the tide in that people genuinely expected the Welsh language to have been destroyed by now," Schiavone said.

Listen to an introduction to Hawaiian in that language.

Learning by example (Ke aʻoʻia e kahi hiʻohiʻona)

Far from being on the verge of extinction, Welsh is often held up today as an example of how grassroots organizing and government support can revive a language.

This was the case in Hawaii, where indigenous language activists were facing a much harder task than their Welsh counterparts, according to Gary Holton, a researcher with the Endangered Language Project

"Almost everywhere the language had ceased to be a first language," he said. "The break in transmission was fairly complete, it required a real effort to jump start the language again ... you had to essentially skip a generation, bring in these grandparents and great-grandparents and get them to interact with preschool-age children."

Ekela Kaniaupio-Crozier was one of the people who helped turn it around. A native Hawaiian speaker, she was a rarity among her school friends, and remembers being the only child attending a language class run by a local church. Despite this, she still struggled to overcome prejudices baked into Hawaiian society against the state's indigenous language.

"I was raised by my grandmother to speak the language. She was very adamant that I speak Hawaiian," she said. "Because I thought it was strange I didn't really choose to speak it back to her but I understood everything."

After university -- in which she trained as a Hawaiian teacher -- Kaniaupio-Crozier became involved in the statewide campaign to revitalize the language. That project has seen remarkable success , leading to a generation of new second-language speakers who are able to pass Hawaiian on to their own children.

The language has also become popular among non-indigenous Hawaiians, Holton said, and like in Wales, indigenous names have been restored to many locations. Media has also played a role, with public radio broadcasting a " Hawaiian Word of the Day " segment and the state's largest newspaper, the Honolulu Star-Advertiser, running a weekly column in the language.

Now in her late 50s, Kaniaupio-Crozier is at the cutting edge of digital language preservation and promotion.

Along with several other teachers from the Kamehameha School network, she is working alongside a team from the Pittsburgh-based language app Duolingo to create a Hawaiian course for English speakers.

On the Slack messaging app and via Skype, Kaniaupio-Crozier and her colleagues liaise with Duolingo developers to come up with bitesize chunks of Hawaiian people can learn and practice on the go through the app's gamified mobile interface.

"It's been interesting," she said. "We're all language teachers, to try and figure out how to do it on this app has been a real challenge. For us to think in those terms, what's most important to somebody, what do they want to see? We had to think different, approach our language teaching differently."

Myra Awodey, a senior Duolingo community specialist, said minority languages had not been "on our radar" when the app was first launched.

"To have a big impact we were covering the big languages," she said. While there were many requests to add minority languages, developers often couldn't justify focusing on them over more widely used ones.

Irish was the company's breakthrough moment. A team of volunteers built out a database for the language and "blew us away," Awodey said. The course now has almost 1 million active learners, or about 60% of the total number of Irish speakers in Ireland itself . About 4 million people have used it at some point, Duolingo said.

Since then, Duolingo has added Welsh (330,000 active learners), Esperanto (380,000), and the South American minority language Jopara (340,000), as well as High Valyrian and Klingon, two made-up languages from the TV shows "Game of Thrones" and "Star Trek" respectively.

While serious concerns have been raised over the risk of " digital language death " -- whereby indigenous languages are not used on modern communication platforms, hastening their demise -- technology also plays a role in preserving languages. Apps and games, along with YouTube shows and podcasts, are new and increasingly successful ways of keeping a language alive and vibrant.

David Hand, the Welsh-speaking Hong Konger, said the previous proliferation of Welsh-language books, music, TV shows and films all helped keep the language alive. Hand runs the St David's Society of Hong Kong , which organizes events for Welsh speakers and expats in the city, as well as fundraising for charity.

"One of the challenges of course about reinforcing (a) language is not to be backward looking," he said. "To make it a living language rather than something to be protected."

But while both Welsh and Hawaiian are seeing a major resurgence, in Hand's adopted home there is increasing concern and paranoia about the future of the city's own native language: Cantonese.

Listen to an introduction to Cantonese in that language.

Language preservation (語言保育)

Nestled at the foot of Castle Peak in Hong Kong's northwest New Territories, the huge white-brick expanse of Harrow International School looms over large green football fields. Students wearing blazers and straw boaters pass under neoclassical arches as they head to class inside the boarding school, reminiscent of a foregone era.

But while its look may be old fashioned, Harrow has found itself embroiled in a thoroughly modern controversy. Earlier this year, the school announced it was dropping the traditional Chinese characters used in Hong Kong and Taiwan in favor of the simplified versions favored in China.

In a letter to parents, Harrow defended the move as necessary "to prepare our pupils to be fully literate in the context that Hong Kong will be in by 2047." That is when the city's current constitutional arrangements expire and it could lose its semi-autonomy and be fully absorbed into China.

Institutional support for education was pivotal in the revival of Welsh. It's an approach that has been adopted in Hawaii, Iceland and New Zealand, where the government has pledged to make Maori a core subject in all schools by 2025.

However in Hong Kong, many fear Cantonese is heading in the opposite direction. Language has become a key battleground for those pushing back against encroachment from China and seeking to emphasize the city's unique identity in the shadow of its much larger neighbor.

Some 144 Chinese languages are listed as in danger by UNESCO, with 24 on the verge of extinction -- including Manchu, the language spoken by the country's former imperial masters.

That Cantonese could follow suit can seem alarmist, bordering on ridiculous. About 90% of Hong Kongers -- some 6.8 million people -- speak it as their first language, and a further 73 million people worldwide speak Cantonese or a closely related dialect.

Yet the fear is that just as English pushed out Welsh as the dominant language of Wales, Mandarin -- the official language of China -- will increasingly replace Cantonese in Hong Kong, sending the latter tongue into decline.

In the past decade, schools across Hong Kong have been encouraged by the government to switch to using Mandarin rather than Cantonese as the primary language in Chinese lessons, which officials say is intended to "enhance the biliteracy and trilingualism of students."

While less than 20% of primary schools and only 2.5% of secondary schools use solely Mandarin to teach Chinese -- with the majority using a mix of Cantonese and Mandarin -- the figure is growing. Supporters of the policy say Mandarin competency increases the competitiveness of Hong Kongers in the job market and enables them to operate in China, where Cantonese is not widely spoken.

There was outrage in October when Education Secretary Kevin Yeung suggested that continued use of Cantonese over Mandarin in the city's schools could mean Hong Kong would lose its competitive edge in the future.

Concerns about Cantonese were on display in "Ten Years," a hugely popular Hong Kong movie anthology released in 2016 which predicted a dark future for the city under Chinese rule . In one chapter titled "Dialect," a taxi driver finds himself unable to work after a regulation requires fluency in Mandarin and marginalizes native Cantonese speakers. The man's son speaks primarily Mandarin, and the pair find it hard to communicate in Cantonese.

This is already happening across the border in Guangdong province, the region of China where Cantonese (Gwongdungwa) originated. National government policies have been aggressive in pushing Mandarin as the medium of instruction in schools, often at the expense of regional languages and dialects. Television broadcasts and other media have also switched to Mandarin, and most young people in China use Pinyin, a system of inputting Chinese characters based on Mandarin, when they communicate online.

"What is happening with the renaissance of Welsh is the polar opposite of Cantonese," said Marco Kwan, editor of Words.hk, a website dedicated to documenting how the city's language is used in daily life. "To preserve or promote or kill a language is largely dependent on educational policy."

While he says many defenders of the language overstate the risk it faces, Kwan is wary of a "top-down aversion to Cantonese." He says this is largely down to city officials and schools seeking to curry favor with the Chinese government by promoting Mandarin teaching in its stead.

On the other side of the debate, he pointed to a "worrying tendency to frame Cantonese as an integral part of the separatist movement, or a revolutionary element, which will make it harder to garner funding and be all the more detrimental to its development."

Holton, the endangered language researcher, was also skeptical of whether Cantonese could ever enter fatal decline due to the sheer number of first-language speakers in the Chinese diaspora. Nevertheless, he was sympathetic to the concerns expressed by many Hong Kongers, and said it was important even for speakers of major languages not to be complacent.

"Language survival is not just about taking speaker numbers into account," Holton said. "Is it used in education, is it used in commerce, or is it only used in the home?

"If policy doesn't support the language, then that makes it difficult regardless of the number of speakers."