Facebook is becoming a key source of news for users of the huge social network, even if people discover articles mostly by happenstance, according to a new study.
The Pew Research Center study, in collaboration with the Knight Foundation, found 64 per cent of US adults use Facebook, and nearly half of those get some news from the service.
That amounts to 30 per cent of the overall US population who are "Facebook news consumers", Pew said.
But the survey found 78 per cent of this group get news mainly when they are on Facebook for other reasons, such as checking on friends or sharing photos.
"People go to Facebook to share personal moments - and they discover the news almost incidentally," said Amy Mitchell, Pew Research Center's director of journalism research.
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"The serendipitous nature of news on Facebook may actually increase its importance as a source of news and information, especially among those who do not follow the news closely."
Most heavy news consumers do not describe Facebook as their main source of information on current affairs:
Some 38 per cent of Facebook news consumers who say they follow the news "all" or "most of the time" describe the social network as an important way they get news.
But that number rises to 47 per cent among those who say they follow news just "some of the time" or less.
Those in the 18- to 29- year-old age bracket account for about a third of Facebook news consumers - often turning to the social network for breaking news.
The study authors write that Facebook "exposes some people to news who otherwise might not get it" by delivering news through shared links from friends.
"This study adds to our understanding of the way social media is transforming how news is shared and consumed," Knight Foundation vice president Mayur Patel said.
"The implications for media organisations are significant - through the data they can gain insights on the behaviour and preferences of the people they are trying to reach, and identify new engagement opportunities."
Roughly two-thirds of Facebook news consumers say they at least sometimes click on news links, and 60 per cent at least sometimes "like" or comment on stories.
About four in 10 post or share links themselves, and 32 per cent discuss issues in the news with other people on Facebook, the survey found.
