Dave Lee Technology reporter, BBC News, tells the story of how amateurs can get it tragically wrong.
For the past 48 hours, he says, internet users have been working with each other to piece together clues about the culprits of the Boston bombings. The result? They got it wrong - and left innocent people fearing for their safety.
A young man named Sunil Tripathi was one "suspect" (read "victim") picked out by thousands of internet users who were discussing their theories and "leads" within massive communities such as Reddit, 4Chan, Facebook and Twitter.
Another "suspect" was 17-year-old Salah Barhoun, described on Reddit simply as Blue Robe Man, thanks to the tracksuit top he had worn.
Users posted information relating to his whereabouts, and pointing out the "sagging" in a shoulder bag he was holding - a sign, some thought, that he was carrying something heavy.
Hours later, the same pictures that had circulated on Reddit and 4Chan found their way to the front page of the New York Post.
Under the headline "bag men", Mr Barhoun and a friend were said to be wanted for questioning - but the tabloid added: "There is no direct evidence linking them to the crime."
The pair were not involved in the bombing - and Mr Barhoun told ABC News he now fears for his life.
There were more: White Hat Black Jacket Guy, Blue Duffel Bag Guy and Green Hat Guy, to share a few.
With each suspect, a rush to find their real identities - and in some cases, social media profiles and groups were peppered with threatening messages.
On Friday, those efforts ended with an apology. After hours of chatter and speculation, the standout suspect identified - and named - was the wrong man.
"I'd like to extend the deepest apologies to the family of Sunil Tripathi for any part we may have had in relaying what has turned out to be faulty information," wrote Reddit user Rather_Confused.
"We cannot begin to know what you're going through and for that we are truly sorry.
"Several users, Twitter users, and other sources had heard him identified as the suspect and believed it to be confirmed.
"We were mistaken."