Answers to some of the most common questions below:
Is Instagram tracking my outside activity, too?
"I am on Instagram, but not Facebook. Is there a way to look at the equivalent 'Off-Facebook Activity' from Instagram directly?" asks Deborah Kaplan from Massachusetts.
Instagram is worse than Facebook when it comes to transparency.
Facebook owns Instagram, and the two apps share tracking technology. When businesses and organizations pass your activity to Facebook, they're also passing it to Instagram. The photo-oriented social network doesn't use its own tracker pixels and cookies - it's all run through Facebook.
But so far, Instagram doesn't have its own "Off-Instagram Activity" portal for you to look at the data Facebook collected for it. To see the data - and to tell Instagram to disconnect it from your account - you must use the Facebook website or app. That means you'll need a Facebook account.
What happened to other apps on Facebook?
"How do I follow the instructions to stop Facebook from sharing my data, yet allow me to view my Washington Post posts in Facebook?" writes Mark Weeks from Bradenton, Florida.
Before you disconnect your off-Facebook activity from your account, Facebook pops up a warning that it comes with a consequence: "This will also prevent you from logging into apps and websites with Facebook because your activity will be disconnected from your account." For some people, that means losing access to games and websites they've previously accessed with a Facebook log-in.
We're learning about one less obvious side effect: Facebook will forget your log-in and password to news websites. So when you click on links to articles from The Post and other outlets in your News Feed, you won't be automatically linked to your subscriptions.
I'm afraid there's no simple way to reteach Facebook your log-ins without re-enabling off-Facebook activity - and all the tracking that comes with it.
How do I quit Facebook?
"How can I close my Facebook account?" asks another reader. "I spent hours looking for a link without success."
You didn't think Facebook was going to make saying goodbye easy, did you?
You'll need to go to Facebook's special page for permanently deleting your account.
Facebook, though, will try to persuade you to temporarily deactivate your account instead. That's the only way you can keep your Facebook Messenger account going.
Does Facebook still track me when I don't have an account?
Tom Hall from Santa Fe writes to say he shut down his Facebook account last year. "Are they still tracking me? If so, can I do anything?" he asks.
Sadly, there's little stopping Facebook's surveillance system.
Facebook gobbles up whatever information its business partners send its way - it doesn't matter if you have an account. That could include your email address, phone number or other ways to identify your phone or computer, all tied to your activity on other apps and websites.
But after you delete your Facebook account, that data should no longer be tied to you. If "you don't have an account with us, we can't identify you based on it," says Facebook spokeswoman Catherine Anderson.
Daniel Kahn Gillmor, a senior staff technologist at the American Civil Liberties Union, wrote to say "deleting the account is certainly a useful and important step, but it's no substitute" for taking other defensive measures. Facebook isn't the only problem - there's a whole industry of data trackers and complicit businesses all tailing you.
Two first steps: Use a Web browser that blocks trackers by default, such as Mozilla Firefox or Apple's Safari. Then, be more selective about what apps you run on your smartphone and what data you allow them to access. I conduct a regular app census where I delete the ones I don't use and remove access to my location and other sensitive data from the ones I keep.
Until there are clearer privacy laws in the US, protecting yourself is going to remain an arms race.
- Geoffrey Fowler is the Washington Post's technology columnist.
