Trump, Twitter and his 'filter bubble'
Although his main Twitter account has nearly 44 million followers, President Donald Trump chooses to follow just 45 other Twitter users - all of whom agree with him, most of the time.
Now that seeming reluctance to expose himself to alternative viewpoints is being put forward as a possible factor in the president's decision to retweet three videos by a far-right UK group.
Social media experts call it the "filter bubble" - the ability to choose only the news and views that we agree with.
Earlier this year, Microsoft founder Bill Gates warned against the negative effects of the filter bubble, which he said increasingly prevented people from "mixing and sharing and understanding other points of view".
"It's turned out to be more of a problem than I, or many others, would have expected, " he told the Quartz website.
Sometimes the bubble is automatic, created for us by a combination of our browsing history data, plus the algorithms of Facebook and Google. The end result: posts, people and stories that conform to our individual world view.
Sometimes we get to build our own bubble, by deliberately cutting ourselves off from dialogue with people who don't agree with us.
- What do the videos Trump retweeted actually show?
- Trump wrong to share far-right videos - UK PM
- Why is Britain First big online?
If Wednesday morning followed the president's typical routine, he woke up, turned on the TV and opened Twitter on his phone.
Shortly afterwards, the worldwide outrage started.
Although the White House has refused to discuss the "process" by which the video was shared, most observers think it was the president who chose to retweet the video "Muslim migrant beats up Dutch boy on crutches!"
The authenticity of that video has now been challenged.
The anger deepened when it was confirmed the three videos had originally been shared by the deputy leader of an anti-immigrant, anti-Muslim group - Britain First.
They had made their way onto the president's feed - it's thought - via one of the few people the president follows on Twitter: right-wing commentator Ann Coulter.
Ms Coulter is one of the 45 Twitter users that the president "follows" on his most effective communication tool - @realDonaldTrump has 43.7 million followers
But compared with his predecessor, Mr Trump follows a tiny number of other users.
Barack Obama - with 94.7 million Twitter followers - follows 626,000 other Twitter users.
Mr Trump, on the other hand, is much more selective about who he follows.
Trump also uses another Twitter handle, @POTUS (president of the United States) which follows 41 other accounts, mainly family and government departments. He tends to tweet less frequently from this account.
You can recreate the president's @realDonaldTrump feed here https://twitter.com/trumps_feed, courtesy of the Washington Post.
It may be, however, that Mr Trump does expose himself to other viewpoints, according to social media marketer Alex McCann (@altrinchamhq): "We have to remember that he has hundreds of thousands of notifications every day of people replying to his tweets."
"Hopefully he does check these and get a bigger picture than presented by his curated feed of the 45 people he follows. He may have created a Twitter list as well that might give more variety, but we don't know." (No public lists are available on @realDonaldTrump.)
"But if he is restricting himself to 45 people that's going to create a very monotonous feed - an echo chamber of people that agree with you."
Golf, wrestling and the Apprentice
Amelia Tait (@ameliargh), tech and digital culture writer at the New Statesman, said that compared with a "normal" user, Mr Trump follows very few people on Twitter.
"This isn't necessarily surprising, as he has always used the site as more of a place to talk rather than listen.
"It could have troubling implications about what he sees and interacts with, though. It's been theorised he saw the Britain First tweets via Twitter's "in case you missed it" tool. Had his feed been busier, he might have missed that too!" she said.
On the @realDonaldTrump's "following" list are seven family members, including wife Melania, his children, and two daughters in law.
He follows four government departments, such as the Department of State, and eight Trump commercial organisations such as his main company, five golf courses and two Trump-branded hotels.
Current and former employees include Vice-President Mike Pence, White House spokesperson Kellyanne Conway and White House press secretary Sarah Sanders also feature.
There are a smattering of "others", including people Mr Trump has worked with before he became president - like World Wrestling Entertainment boss Vince McHahon and former Apprentice star Katrina Campins.
Veteran golfer Gary Player is also on this list. Player has previously praised Mr Trump's game, telling CNBC in October: "The strength is his length, he's a long hitter. He can really get the ball out there."
But by far the largest subset of people and organisations that Mr Trump follows is made up of conservative journalists and TV presenters.
Ten of them work, or have worked, for the conservative news channel Fox News, like Bill O'Reilly and Eric Bolling - both of whom left Fox following allegations of sexual misconduct.
Staunch Trump defender Sean Hannity is also on the president's "follow" list.
The show Fox and Friends - thought to be a major opinion former on the president - is on the list.
Fox and Friends has been known to cover a story, only for the president to tweet on the same story a few minutes after the programme ends - and sometimes while it is still on air.
Ms Tait said: "Trump's Twitter feed is most definitely an echo chamber, which is problematic for someone in an elected office who is ostensibly the voice of the people.
"He frequently criticises 'fake news' TV channels but has never rebutted any number of viral tweets calling him out. Is it possible he never saw them?"
However, Alex McCann believes that Trump is only doing what comes naturally.
"Most people gravitate towards opinions they share," he said. "It might be more healthy to consume different opinions. But it will make you more angry.
"Twenty years ago our parents did the same thing - only they bought newspapers that conformed with their world view."
But Mr McCann believes leaders have a special responsibility to step outside of the filter bubble.
"Leaders are supposed to represent everyone," he said. "Not just the people who agree with them."