Mark Zuckerberg spent much of his Congressional testimony making the case that Facebook users have control over their data. But what about the data the social network collects from people who don't even have accounts?
In Congress last week, Zuckerberg said Facebook needed to track people who weren't members for "security purposes." In a follow-up blog post Monday, the company laid out plenty of business reasons to do it too.
Facebook said other websites and apps use its services to let people quickly create accounts and later share content on their Facebook pages, like news articles. Behind the scenes, Facebook also helps some sites and apps track their performance and run ads from Facebook advertisers.