Facebook will start tracking non-users across the web, in its latest step towards conquering the online advertising space.
Facebook delivers ads to many mobile sites and apps beyond its own using what it calls the Facebook Audience Network, a system similar to Google's AdWords and other advertising platforms.
Companies can use the targeted data they get from Facebook and take it to other places. For those of us with Facebook accounts, this has meant Facebook's targeted adverts has been following us around the web.
From today, those without accounts will also be targeted by advertisers in the Audience Network.
Facebook will do this by installing cookies on people's browsers, which will monitor your activity to better serve ads that are relevant to your interests - or what it thinks your interests are, based on what you've been looking at.
Facebook is doing this to both improve people's experience with ads, and also help advertisers hone in on the right people.
It believes its knowledge of people's interests puts it in a position where it can offer a better advertising experience across the web for everyone.
"Advertising may be here to stay, but bad advertising like this doesn't have to," wrote Ads and Business Platform VP Andrew Bosworth, in a blog post.
"That's why we're working to provide a better online advertising experience for everyone: people, publishers, and advertisers."
If you have a Facebook account and want to opt out of tracking, you can do so by going into your Facebook Settings.
Non-users can opt out via the Digital Advertising Alliance site (the links can be found on Facebook's site ) or, if you're on a phone or tablet, you can prevent it through your device settings.
Alternatively, you can click the AdChoices icon next to any ad served through the Audience Network.
If you're in the EU and visit Facebook from today, you'll be met with a banner along the top of the page informing you that the site is using cookies, which shows to comply with EU law.