Lawmakers from both parties attacked online platforms for causing offline harm to children, public health and democracy at a House hearing with the CEOs of Facebook, Google and Twitter testifying virtually on Thursday.

The big picture: The hearing is focused on social media's role in spreading misinformation and extremism, with the Jan. 6 insurrection at the U.S. Capitol and false information about the pandemic top of mind for Democratic lawmakers who have pledged to pursue legislation.

Social media giants keep trotting out jaw-dropping stats about fake accounts and rule-violating posts they're removing. But the number that matters most is how much misinformation remains up. 

Driving the news: CEOs of Facebook, Google and Twitter will recite more numbers Thursday, when their CEOs testify at a marquee hearing before a Congressional committee investigating online misinformation.

Social media giants have taken a number of steps to try to clear misinformation off their platforms, but those efforts aren't likely to appease furious lawmakers in both parties.

What's happening: When they testify virtually before House lawmakers on Thursday, Facebook CEO Mark Zuckerberg, Google CEO Sundar Pichai and Twitter CEO Jack Dorsey will point to recent company policy changes to argue they're doing what they can to stem the tide of misinformation and extremism online.

Native American tribes are pulling off many of the most successful coronavirus vaccination campaigns in the U.S., bucking stereotypes about tribal governments.

The big picture: Despite severe technological barriers, some tribes are vaccinating their members so efficiently, and at such high rates, that they've been able to branch out and offer coronavirus vaccines to people outside of their tribes.

Artificial intelligence is becoming a true industry, with all the pluses and minuses that entails, according to a sweeping new report.

Why it matters: AI is now in nearly every area of business, with the pandemic pushing even more investment in drug design and medicine. But as the technology matures, challenges around ethics and diversity grow.

Congress' effort to squelch misinformation is broadening to target the cable companies that bring right-wing networks like Newsmax, OANN and Fox News to Americans' screens.

Why it matters: Conspiracy theories, false election claims, anti-vaccination propaganda and other kinds of misinformation spread through a complex ecosystem: Lies bubble up online, then get amplified when cable news channels repeat them, then spread further via social media. Breaking the cycle will require more than just stricter content moderation by online platforms.

Wall Street's populist uprising, the Capitol siege and a strong U.S. anti-vaccination movement show the power of memes in spreading misinformation and influencing communities online.

Why it matters: For years, there's been growing concern that deepfakes (doctored pictures and videos) would become truth's greatest threat. Instead, memes have proven to be a more effective tool in spreading misinformation because they're easier to produce and harder to moderate using artificial intelligence.

Health officials are worried that misinformation about the COVID-19 vaccines and infertility will drive down vaccination rates among women, the Washington Post reports.

Why it matters: False claims about the vaccines are rampant, and threaten to prevent the U.S. from vaccinating enough people to put the pandemic safely behind us.

China, Russia and Iran — drawing on one another’s online disinformation — amplified false theories that the COVID-19 virus originated in a U.S. bioweapons lab or was designed by Washington to weaken their countries, according to a nine-month investigation by AP and the Atlantic Council’s DFRLab.

Why it matters: Through a series of overlapping, if slapdash, efforts, America's global adversaries benefited from mutually reinforcing counter-narratives propagated online that aimed to falsely place responsibility for the pandemic on the U.S. and often to sow doubt on its actual origin within China.

Facebook on Monday became the latest in a run of tech firms and media outlets taking action to stem the tide of COVID-19 vaccine misinformation, but experts worry the scramble to limit vaccination skepticism may be too little, too late.

Why it matters: "With all of these press releases, what we don't understand is, how is it actually going to be operationalized?" says Claire Wardle, the U.S. director of anti-misinformation nonprofit First Draft. "Anti-vaxxers have historically always figured out where the policy guidelines are and figure out a way around them."