Here are some of Zuckerberg's claims, as well as some claims from the lawmakers, which we fact checked.
Asked if Facebook executives have been interviewed by special counsel Robert Mueller, who is investigating Russian interference in the USA election: "Our work with the special counsel is confidential...." The company is accused of using that data to influence the 2016 elections.
Does Facebook track you even when you're not logged in? "Your content has to be authentic." .
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More than one senator brought up the question of whether Facebook suppresses conservative viewpoints, and none was more aggressive about it than Cruz. "I do think it mattered, just because it was information that was so detailed".
Zuckerberg told senators he did not see the Cambridge Analytica episode as a violation.
"Um... no", Zuckerberg said after pausing, then smiled as the room laughed.
We only access your microphone if you have given our app permission and if you are actively using a specific feature that requires audio. Richard Blumenthal, D-Connecticut, whose aides displayed an enlarged section of the Terms of Service for "This Is Your Digital Life" app.
"The most important thing I care about right now is making sure no one interferes in the various 2018 elections around the world", he testified before a 44-Senator panel.
"In principle, I think that that makes sense, and the details matter, and I look forward to having our team work with you on fleshing that out", Zuckerberg said. The other says that your data was "misused" and shared with Cambridge Analytica.
Is this too little, too late or does this really affect Facebook usability in any way?
Zuckerberg could not give a straight answer as to whether Facebook tracks the browsing activity of its users after they log off.
The devices have been speculated to cost an upwards of $499 (£370), making them much pricier than similar products now on the market, such as Amazon's $39 (£27) Echo Dot. For example, the senator asked "Can I believe what I am seeing [on Facebook]?" and "Who has access to this information about me?"
Yes, there were questions about what the company should change or what it should have reported earlier. Facebook did recently endorse this legislation.
Facebook disclosed in September that Russians under fake names used the social network to try to influence US voters in the months before and after the 2016 election, writing about inflammatory subjects, setting up events and buying ads.
Asked if he believes the social media giant, with over two billion users worldwide, amounts to a monopoly: "It certainly doesn't feel like that to me".
Facebook has added this feature to its help center page. This information can be drawn into Facebook's vast data aggregation machine through friends or friends of friends via all kinds of channels, including the "find friends" feature that allows the app to scan mobile contacts. The qualifiers in those statements - "version", "today" - suggest a future, ad-free version of Facebook could come with a subscription fee.
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