Happy Nice Mall

The hearing with Facebook informant Frances Haugen covered much more ground than previous congressional hearings with social network executives. This may be because Ms. Haugen, 37, a product manager who worked at Facebook for two years before leaving in May, spoke more freely.

Here are the three main takeaways from the day:

• Republican and Democratic lawmakers united to take action to stop the harm being done to young people on Facebook. Lawmakers debated how Facebook knows about the harm apps like Instagram are doing to teens, citing internal research unearthed by Ms. Several senators debated their proposed bills that would add safety provisions for younger users.

  At one point, Ms. Haugen proposed something even more radical: raising the minimum age for anyone using social media from 13 to 17.

• Lawmakers have gotten smarter about technology. Lawmakers at the hearing explored the role Facebook’s algorithms play in boosting problematic content, and the way the company continually tweaks its algorithm to favor one type of content over another.

  This is much more complex than the kind of questions lawmakers have asked about Facebook before. (Remember a few years ago, when some lawmakers didn’t know how the company made money?) While past hearings focused on specific topics, such as online conversation or whether a particular person or idea should be banned from platforms, the discussion at Tuesday’s session was broader and actively played by Facebook in pieces of content it promoted. He touched on many aspects of the role.

  This was supported by Ms. Haugen’s frankness. He used his knowledge of Facebook technology to explain how algorithms work in the language of the non-ordinary and sparked a nuanced discussion of what lawmakers could do in the future.

• Facebook sits on an even bigger mountain of internal research. The thousands of documents Ms. Haugen submitted to MPs are probably just the tip of the iceberg. In his statement, he encouraged lawmakers to request more documentation and internal research from Facebook, and stated that only through complete transparency can Congress hope to understand and ultimately regulate social media.

  Ms. Haugen also hinted that more would come from her. During the hearing, he said he spoke with a separate congressional committee about how critical security teams that monitor whether countries are using the platform to spy on each other and run disinformation campaigns fall short on Facebook. He said the company did not adequately protect against threats from China, Iran, Russia and other countries.