Facebook is "dead and buried" to young people, who are deserting the site in droves to avoid watchful parents, in favour of simpler social networks, according to new research.
Teenagers are gravitating towards mobile-first apps such as WhatsApp, Twitter or Snapchat because they are much easier to use, according to the Global Social Media Impact Study.
Professor Daniel Miller, who worked on the reseach funded by the European Union, said: "What we've learnt from working with 16- to 18-year-olds in the UK is that Facebook is not just on the slide, it is basically dead and buried."
Miller said they were logging off Facebook to avoid using the same site as their families and to regain some privacy. They were switching to sites such as Superchat, which leaves no permanent record.
Miller, one of a team of eight ethnographic researchers at University College London, found young people's use of social media varied across different sites.
"In my school research, the closest friends are connected to each other via Snapchat, WhatsApp is used to communicate with quite close friends, and Twitter the wider friends. Instagram can include strangers and is used a little differently," Miller said.
"Facebook, on the other hand, has become the link with older family, or even older siblings who have gone to university."
He added few schoolchildren would go as far as to close their accounts but were using it mainly to keep in touch with older family members.
"I don't expect Facebook to necessarily disappear altogether, but I think it's finished for the young in the UK."
Professor Miller and his team worked on the EU-funded study in seven countries including Brazil, China, India and the UK to examine social media trends. They examined topics including how people connect via the internet, variations in social media use regionally and what contribution social media has made to political developments such as the Arab Spring uprisings.