This is how Facebook uses your data for ad targeting

Facebook collects a lot of data about you — everything from your email address to the strength of your phone’s battery.

The simplest explanation for this is that Facebook uses that data to make money. No, Facebook doesn’t sell your data. But it does sell access to you, or more specifically, access to your News Feed, and uses that data to show you specific ads it thinks you’re likely to enjoy or click on.

This targeted advertising is big business for Facebook. The company reported advertising revenue of $40 billion last year, and it’s only going to keep growing. Given the company’s recent privacy issues involving Cambridge Analytica, a third-party data firm that got its hands on personal data for as many as 87 million Facebook users without their permission, we thought it might be helpful to take a closer look at how Facebook uses your data to make money.

It’s also clear that many people don’t know the details of how Facebook’s advertising business works. Many of these questions were asked by lawmakers on Tuesday when Facebook CEO Mark Zuckerberg testified before Congress in Washington, D.C.

Some of these answers can be found in the company’s Data Policy, which Facebook just updated to better explain what it collects and how it’s used. We also asked a company spokesperson for responses to all of these questions. Those answers are summarized below.

Does Facebook sell your data?

No. Facebook uses your data to sell access to you. For example, it will put an ad in your News Feed, but it doesn’t sell the data you provide to outside buyers. That makes sense when you stop and think about it. Facebook’s business is valuable because it has so much personal data about its users. Selling that data to advertisers would significantly decrease Facebook’s value.

Does Facebook share your data with businesses or advertisers? When?

Outside businesses can collect your data if you grant them permission — for example, if you use your Facebook account to log in to a third-party app like Uber or Spotify. Facebook just announced changes to some of those data-sharing APIs to better ensure that agreeing to share your own data won’t let those outside companies collect data about your friends without their permission. (This is what happened with the Cabridge Analytica situation.) Of course, any data you share publicly to your Facebook page is accessible to anyone online.

How can you see what data Facebook has collected about you?

There are a couple places to look. Visit “Settings” on Facebook, and under the “General” tab you will see an option to “Download a copy of your Facebook data.” Click that. This will give you all of the data Facebook has collected about you, from private messages to photos to your search history.

Under “Settings” you can also click “Ads,” which will bring you to an “Ad Preferences” that includes the interests Facebook thinks you have (and advertisers use to target you), and other information they might use to target you (e.g. the type of phone you use). You can remove interests or information from this page that isn’t relevant or that you don’t want Facebook using to target you.

Do advertisers know if you’ve seen their ad?

Not really. Advertisers can see details about who sees their ads, but only in aggregate. For example, an advertiser could see that their ad reached 1,000 males in San Francisco, but it could not see names of each of those 1,000 users.

Does Facebook use info from your private messages to target you with ads?

No. Facebook says it might look at your private messages to determine if they violate the company’s policies, but it doesn’t use that information for ad targeting. Facebook won’t use the contents of your private messages to target you with ads on Facebook Messenger, WhatsApp or Instagram either, according to a spokesperson.

Does Facebook use your phone’s microphone to listen to you at any time?

The company says no. “We only access your microphone if you have given our app permission and if you are actively using a specific feature that requires audio,” the company wrote on its blog.

Does Facebook use your call history or off-Facebook text message data to target you with ads?

No, Facebook does not use this data to target you with ads, according to a Facebook spokesperson. Facebook can see the call and text history for Android users who opt in to let the company see that data. It also says it doesn’t use it to recommend friends you might like to connect with.

Does Facebook use the same set of data to target you with ads on Instagram that is uses to target you with ads on Facebook?

Yes. What you do on Instagram could lead to ads you see on Facebook, and vice versa. “The same interest-based targeting available to advertisers who target ads to people on Facebook is available for Instagram ads,” a company spokesperson told Recode. “This includes interests based on the things people do on and off Facebook.”

Does Facebook use the same set of data to target you with ads on Messenger that it uses to target you with ads on Facebook?

Again, yes. “Messenger Ads (ads placed in people’s Messenger home screen) use the same audience targeting options as Facebook ads,” a spokesperson says.