Facebook has added a new 'setting' letting people choose whether or not they want to be tracked and shown adverts.
It comes after the social network said it would add ads that track and were used across all the internet - even if you did not have a Facebook profile or page.
Facebook has said it does let people switch off the tracking, but users have to actually opt out of the system and manually turn it off.
The site has always offered people the option to stop other websites and apps from using their preferences to provide advertising.
Data is collected from tracking people when they move around Facebook, it's then used to work out what they may like or be interested in.
While it all sounds fairly terrifying, it can be turned off by going to Facebook's ad settings page.
To see how to opt out scroll down
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Associated professor of media design David Carroll spotted the move, sharing it on Twitter .
He told people to check privacy settings because Facebook had "opted you back in without notice or consent”.
But Facebook hit back in a tweet saying: "We didn't change our settings."
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The site says it is a new control that is being offered for the first time, directing people to Facebook's post about the new ad network.
The post explains the social network is adding new tools that allow it to show ads across the internet.
It also said it was adding an option that allows people to stop being tracked.
Professor Carroll clarified what he meant in a Medium blog saying: "When Facebook added its new 'control,' they require us to find a means to gain the knowledge that it exists and then turn it off again in its varied context that might seem obvious and significant to an industry insider but is otherwise a subtle nuance for everyone else."
He added: "“Rather than carry over my existing choice, which would logically preserve any goodwill with the company, they were greedy and defaulted us all back in to tracking and targeting in an even more expansive manner than we could previously imagine."
What to do to opt out
Go to your Facebook settings - which looks like this:
Click Adverts on the left side bar.
Switch the yes to no for each option.
That's it.
What about how Facebook determines what adverts to show me?
To check in more detail what Facebook is using to provide adverts, you can click 'Your Advert Preferences'.
You will see a list and then you can add and remove your preferences - Facebook will use this to show adverts they think are more relevant.
(Warning: The list will reveal what Facebook thinks of you, from your humour to shows you like, and businesses they think you'd like....it's a little bit terrifying)
The more you remove the less options there are for them.
You will still get adverts, they will just be less tailored.