This story is part of, CNET's coverage of the voting in November and its aftermath.
Facebook, Twitter and YouTube are battling waves of misinformation after the presidential election was called on Saturday morning for , who won the popular vote and has garnered more than 5.1 million votes across the US than his rival.
Among the biggest challenges: President Donald Trump, who's been using social networks to falsely claim, without evidence, that the 2020 election was "stolen" from him. Twitter quickly appended cautionary notes to five of seven Trump tweets on Saturday morning, including one in which the president wrongly claimed he had won. The tweets were posted before major news organizations, including CNN, NBC and Fox, made their election call for former Vice President Biden.
One of two later tweets, in which Trump baselessly claimed "BAD THINGS" had happened during the count, was labeled as disputed. Clicking on the label takes users to a page that calls voter fraud "exceedingly rare." The following day, Trump blasted out eight tweets, six of which were labeled. Since then, the president has continued to tweet and re-tweet items the social media network has appended with warning labels -- even as state regulators from both political parties are saying there's no evidence of fraud or other irregularities that would have favored one candidate over another.
Other challenges for the social networks include imposter accounts posing as credible news organizations, live streams broadcasting bogus results and fake reports of Sharpies being used to suppress votes. (No, using a Sharpie didn't and doesn't invalidate your ballot.)
Misinformation after the Nov. 3 election has gotten so bad that Christopher Krebs, the director of the US Cybersecurity and Infrastructure Security Agency, took to Twitter to urge voters to think twice before forwarding a false internet rumor about a supercomputer altering votes. (The rumor, known as "Hammer and Scorecard," has an inglorious backstory, according to Snopes.)
The three big social networks -- Facebook, Twitter and YouTube -- have established policies for dealing with misinformation, from applying labels to questionable info to deleting posts and banning users. The election continues to keep them busy.
All the networks label questionable posts and remove falsehoods if the content has the potential to incite violence. Facebook takes a more hands-off approach to posts from politicians than, which has limited the reach of Trump's tweets. On all election-related videos and search results, YouTube applies a warning that results may not be final.
Here are some of the most significant cases of misinformation and how the social networks responded.
- By far the biggest challenge the social network faced has been handling posts by Trump, who used Facebook to question results as soon as the polls closed on election night. A post late on Nov. 3 by the president alleged without evidence that he was "up BIG" and his political opponents were "trying to steal the election." Facebook labeled the post with information that the vote count was ongoing and directed users to an election information center. More than 101 million US voters cast ballots early -- either in person or by mail -- because of concerns about voting in person during the coronavirus pandemic, which is why election officials were already prepared for counting to take days if not weeks.
- Facebook continued adding labels to misleading posts by the president as votes were being counted. After major news organizations called the race, some labels on Trump posts identified Biden as the "projected winner." The social network added notes to some Trump posts that reminded users the vote would take longer than usual because of COVID-19 and that election officials follow strict rules.
- Facebook added a label under a video shared on Trump's page in which the president falsely claims, "Frankly, we did win this election." Trump made the comment during a late-night media address that was broadcast on TV on election night.
- The social network shut down a massive group called "STOP THE STEAL" that was spreading false claims that Democrats were trying to rig the election. The group had more than 364,000 members.
- Facebook was recommending live videos to users with election misinformation and Russian state-controlled media content, according to BuzzFeed News. The company pulled down some of the videos.
- Twitter added notes to five of seven Trump tweets on Saturday morning. Four were obscured and required users to click through in order to read them. Some of the tweets baselessly said there was misconduct in the vote count in several close states.
- Twitter added notes to six of eight Trump tweets on Sunday.
- Twitter labeled a Trump tweet that falsely alleged election tampering as "disputed" and potentially "misleading." It also obscured the president's tweet. Users can't like the tweet and can share it only if they weigh in with their own comment.
- Twitter subsequently labeled and obscured several Trump tweets and retweets, including one calling to "STOP THE FRAUD!" There isn't any evidence of election fraud. More than 77 million people cast votes in favor of Biden, while over 72 million voted for Trump.
- Twitter allowed a clip of Trump's false victory claim during an election night television appearance to remain on its platform without a label. Twitter said the video, which was shared by media outlets, didn't violate its policies. The video, shared by the Trump campaign account, has more than 22 million views.
- Twitter suspended a group of accounts that posed as legitimate news organizations. Some of the accounts, which mimicked the Associated Press and CNN, spread false reports that Democrat Joe Biden had won the election before the vote tallies were in. The groups appeared to be working together.
- The Google-owned video-sharing service added a label under the video of Trump falsely claiming victory on election night. The video has more than 414,000 views on Trump's channel. (The label, though, isn't intended only for misinformation. It appears under all election-related videos and search results.)
- YouTube took down multiple videos livestreaming fake election results hours before polls closed anywhere in the country. The video streams, some of which ran ads that made the account holders money, were viewed by thousands of people before being removed. One of the channels carrying a stream appeared to have almost 1.5 million subscribers.
- YouTube has been criticized for refusing to take down two videos by One America News, a far right news organization, that falsely declare victory for Trump. Despite the false claims in the videos, YouTube said they don't violate the platform's rules, which focus narrowly on voter suppression. The platform, though, will no longer show ads on the videos, depriving the network of revenue.