4 TWITTER, INC. v. TAAMNEH Opinion of the Court YouTube, 510,000 comments are posted on Facebook, and 347,000 tweets are sent on Twitter. See Statista, Media Usage in an Internet Minute as of April 2022 (2023), https://www.statista.com/statistics/195140/new-usergenerated-content-uploaded-by-users-per-minute; Statista, YouTube–Statistics & Facts; B. Marr, How Much Data Do We Create Every Day? Forbes, May 21, 2018. On YouTube alone, users collectively watch more than 1 billion hours of video every day. See YouTube Advertising, Reach Your Customers—and Discover New Ones, https://youtube.com/ intl/en_us/ads/how-it-works/set-up-a-campaign/audience. Defendants profit from this content largely by charging third parties to advertise on their platforms. Those advertisements are placed on or near the billions of videos, posts, comments, and tweets uploaded by the platforms’ users. To organize and present all those advertisements and pieces of content, defendants have developed “recommendation” algorithms that automatically match advertisements and content with each user; the algorithms generate those outputs based on a wide range of information about the user, the advertisement, and the content being viewed. So, for example, a person who watches cooking shows on YouTube is more likely to see cooking-based videos and advertisements for cookbooks, whereas someone who likes to watch professorial lectures might see collegiate debates and advertisements for TED Talks. But not all of the content on defendants’ platforms is so benign. As plaintiffs allege, ISIS and its adherents have used these platforms for years as tools for recruiting, fundraising, and spreading their propaganda. Like many others around the world, ISIS and its supporters opened accounts on Facebook, YouTube, and Twitter and uploaded videos and messages for others to see. Like most other content on those platforms, ISIS’ videos and messages were then matched with other users based on those users’ information