From internal leaks within the company as well as external analysis, the tip of the iceberg behind Facebook’s spyware empire is exposed. Take a look to better protect yourself when you’re not even on the platform: https://simplifiedprivacy.com/facebooks-corrupt-off-platform-surveillance/
If third parties agree they can send Facebook plenty of information when you visit to figure out who you are.
Even sharing information, how do they build a profile without third party cookies?
For instance, suppose I visit a travel website on Thursday and a sports website on Friday. Even if they work together, how do they figure that the person who visited on Thursday is the same as the person who visited on Friday? And how would Facebook match that when I visit them in order to serve a travel or sports ad?
If I ban third party cookies, use a VPN, and obfuscate my browser/hardware, then I don’t see how they could build a profile that follows me around the web.
Because things like even the window size connects that data together. Window size, features of the browser http://www.supportdetails.net/ is a non malicious version of it that only shows very basic support details. This is a more detailed version https://browserleaks.com/ even when your browser doesn’t leak data though, that in itself is unique. Specially since Facebook buys ISP data and can connect that x IP made a connect to x VPN.
So that ties all the visits together. From there you then can say well we know from past days that Todd visited this website and that website typically back to back. So this anonymous user data is likely Todd because of the browsing habits Todd has is supported by this data.
Additionally they get third party datas to confirm and tie it together. So they’ll eventually see you login to a website and get those account details like email address. From there they’ve built a full profile on you. Even if some websites are wrong, most of them are correct and that’s all that matters.