I know others have commented on this but it's pretty important that we understand that fake news is not simply something manufactured by 20 year old Macedonians or Russian spies. Throughout our media stories are created based on the flimsiest of evidence. Or indeed on evidence that really doesn't exist at all.
Here, from that impeccable establishment media source, The Economist:
The report does not say what proportion of the 53,000 sample tweets related to Ms Cox’s murder, and what share concerned Brexit more generally. When The Economist asked the authors for help, they declined to share their data with us, citing death threats they said they had received since the report’s release. So we undertook our own analysis, examining tweets from June and July that included the terms “Jo Cox” or “#JoCox”—some 341,000 unique messages. Of a random sample of 800 of these, none was celebratory, and just four seemed to be derogatory toward Ms Cox, criticising her support for Syrian refugees, for instance. From this, simple statistics suggest that the true number of tweets cheering the politician’s murder would lie between 0 and 1,500. (The Hope Not Hate report reproduces about 30.) Mr Awan notes that our sample did not include tweets that mentioned only the killer, Mr Mair; it is also likely that some tweets were deleted before our collection.Now, as the report notes, it's terrible if even one Tweet celebrates a murder but the thrust of media coverage - driven by the original Hope Not Hate press release of this shocking study - was that such activity was commonplace when it wasn't.
We see this pattern repeated by newspapers again and again with the thread of fake news creation often going back to a press release from a worthy organisation like a charity or campaign group. From sugary drinks and booze through to vaping and fracking the misuse of evidence, even the creation of evidence simply to generate a news story, is widespread. Journalists used to challenge and question the claims made by those issuing press releases but it seems today that there's either no time or no inclination to do that basic journalistic job of checking the facts before publishing.