This dataset includes two tables: data on the interest categories Facebook shows to users and the ad groups its shows to advertisers. ProPublica used this data to show that Facebook tells its users a lot of things it knows about them, but not all the things it's selling to advertisers.

Interest category data was compiled using a Chrome extension, built by ProPublica reporters. The extension showed users the interest categories Facebook assigned to them, and gave users the opportunity to share all of these categories with ProPublica. The data shared did not include any identifiable user information. Through this extension, ProPublica crowdsourced 52,235 unique interest categories.

The second table contains data scraped from the company's ad buying portal. This table shows what audiences Facebook allows ad buyers to target.