When I downloaded a copy of my Facebook data last week, I didn’t expect to see much. My profile is sparse, I rarely post anything on the site, and I seldom click on ads. (I’m what some call a Facebook “lurker.”)
But when I opened my file, it was like opening Pandora’s box.
With a few clicks, I learned that about 500 advertisers — many that I had never heard of — had my contact information, which could include my email address, phone number and full name. Facebook also had my entire phone book, including the number to ring my apartment buzzer. The social network had even kept a permanent record of the roughly 100 people I had deleted from my friends list over the last 14 years, including my exes.
How Facebook collects and treats personal information was central when Mark Zuckerberg, the company’s chief executive, recently answered questions in Congress about data privacy and his responsibilities to users. During his testimony, Mr. Zuckerberg repeatedly said Facebook has a tool for downloading your data that “allows people to see and take out all the information they’ve put into Facebook.”
But that’s an overstatement. Most basic information, like my birthday, could not be deleted. More important, the pieces of data that I found objectionable, like the record of people I had unfriended, could not be removed from Facebook, either.
Digging through your Facebook files is an exercise I highly recommend if you care about how your personal information is stored and used. Here’s what I learned.
Facebook retains more data than we think
When you download a copy of your Facebook data, you will see a folder containing multiple subfolders and files. The most important one is the “index” file, which is essentially a raw data set of your Facebook account.
One surprising part of my index file was a section called Contact Info. This contained the 764 names and phone numbers of everyone in my iPhone’s address book. Upon closer inspection, it turned out that Facebook had stored my entire phone book because I had uploaded it when setting up Facebook’s messaging app, Messenger. I opted to turn off synchronizing and deleted all my phone book entries.
Facebook also kept a history of each time I opened Facebook over the last two years, including which device and web browser I used. On some days, it even logged my locations, like when I was at a hospital two years ago or when I visited Tokyo last year.
Facebook keeps a log of this data as a security measure to flag suspicious logins from unknown devices or locations, similar to how banks send a fraud alert when your credit card number is used in a suspicious location. This practice seemed reasonable, so I didn’t try to purge this information.
But what bothered me was the record of “Removed Friends,” a dossier of the 112 people I had removed along with the date I clicked the “Unfriend” button. Why should Facebook remember the people I’ve cut off from my life?
Facebook’s explanation was dissatisfying. The company said it might use my list of deleted friends so that those people did not appear in my feed with the feature “On This Day,” which resurfaces memories from years past to help people reminisce. I’d rather have the option to delete the list of deleted friends for good.
The ad industry has eyes everywhere
What Facebook retained about me isn’t remotely as creepy as the sheer number of advertisers that have my information in their databases. I found this out when I clicked on the Ads section in my Facebook file, which loaded a history of the dozen ads I had clicked on while browsing the social network.
Facebook said unfamiliar advertisers might appear on the list because they might have obtained my contact information from elsewhere, compiled it into a list of people they wanted to target and uploaded that list into Facebook. Brands can upload their customer lists into a tool called Custom Audiences, which helps them find those same people’s Facebook profiles to serve them ads.
Brands can obtain your information in many different ways. Those include:
■ Buying information from a data provider like Acxiom, which has amassed one of the world’s largest commercial databases on consumers. Brands can buy different types of customer data sets from a provider, like contact information for people who belong to a certain demographic, and take that information to Facebook to serve targeted ads, said Michael Priem, chief executive of Modern Impact, an advertising firm in Minneapolis.
Last month, Facebook announced that it was limiting its practice of allowing advertisers to target ads using information from third-party data brokers like Acxiom.
■ Using tracking technologies like web cookies and invisible pixels that load in your web browser to collect information about your browsing activities.
■ Getting your information in simpler ways, too. Someone you shared information with could share it with another entity. Your credit card loyalty program, for example, could share your information with a hotel chain, and that hotel chain could serve you ads on Facebook.
Be warned: Once you see the vast amount of data that has been collected about you, you won’t be able to unsee it.
If you go
The N&O’s Community Voices forum – “Who’s tracking you? Social media and privacy” – will be held at 7 p.m. Wednesday, Apr. 25, at the North Carolina Museum of History. Admission is free and open to the public, but please register in advance at Eventbrite.com.