VOX:

Facebook users just got a new glimpse into — and a little control over — the myriad ways the social network tracks what they do when they’re not using Facebook. If you didn’t already realize it, by the way, Facebook is tracking an astounding amount of what you do when you’re not using the platform, an activity also known as living life in the real world.

The new Off-Facebook Activity tool, which the company announced last August, finally launched on Tuesday. It can tell you which companies are supplying Facebook with information about your real-world activity — for example, that you visited their website or purchased a product from it.

The feature also allows you to opt out of some of this collection — to a point. Clicking on a particular company’s listing will bring up a dialogue that will give you a slightly more specific look at what data was collected. There’s also the option to “Turn off future activity” from that company. If you’re looking for a nuclear option, you can click “Manage Future Activity” and then flip the blue switch on the right side of the page.

I was appalled at how many sites were tracking me using this “feature.” I turned it off immediately.