Here's how Facebook collects your data when you're logged out

The social network can track you through the internet, thanks to Like buttons and Facebook’s Login tool.

Richard Nieva Former senior reporter
Richard Nieva was a senior reporter for CNET News, focusing on Google and Yahoo. He previously worked for PandoDaily and Fortune Magazine, and his writing has appeared in The New York Times, on CNNMoney.com and on CJR.org.
Richard Nieva
2 min read
Thumbs-up sign at Facebook headquarters

Facebook's developer tools can affect you when you're not logged into the social network.

Josh Edelson / AFP/Getty Images

When Facebook CEO Mark Zuckerberg testified before Congress last week, he was asked about the information the social network collects on users -- even if they aren't signed into Facebook.

Zuckerberg began to explain a few of the basics, but eventually said his team would follow up with more information later.

On Monday, the company went into more depth about how it tracks you around the internet.

"When you visit a site or app that uses our services, we receive information even if you're logged out or don't have a Facebook account," David Baser, a product management director, wrote in a blog post. "This is because other apps and sites don't know who is using Facebook."

Facebook's data collection practices have come under scrutiny following a controversy involving Cambridge Analytica, a digital consultancy with ties to the Trump presidential campaign that improperly obtained data on up to 87 million Facebook users without their permission. The data originally came from a Cambridge University researcher named Aleksandr Kogan, who collected the information legitimately through a personality quiz app, but then broke Facebook's terms of service by passing it onto Cambridge Analytica.

Specifically, here are the developer tools that allow Facebook to track you:

Social plugins, like the "Share" or "Like" buttons, which you can find on outside websites, like shopping pages and news articles.

Facebook Login, which lets you log into outside apps using your Facebook account so you don't have to create a new password or username. This is the tool Kogan was using for his personality quiz app.

Facebook Analytics, which gives website owners information on how and when people interact with their site.

Facebook ads and measurement tools, including Facebook Pixel. The tool measures how effective ads are, by giving Facebook information on when you visited certain sites and took specific actions, like buying something.

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