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Let’s say you go to example.com and they’re using a Facebook Pixel for analytics - so example.com can continue marketing that widget to you after you’ve left th

by dfee 9y ago

Let’s say you go to example.com and they’re using a Facebook Pixel for analytics - so example.com can continue marketing that widget to you after you’ve left their site. Well, when you visit example.com/shop/widget1 you essentially load a 1x1 pixel image from the url ads.facebook.com/pixel?metadata=goes-here and you web browser sends your Facebook cookie along side the request (as it does for every request to .facebook.com). So Facebook knows what site you’ve visited and what your interest are so that example.com can better market to you, their prospective customer. The web relies on cookies so you can remain logged in, have a shopping cart, and do most everything else that is stateful (though sometimes this stuff gets implemented in the browser’s webdata cache called localStorage). The container effectively makes the “session” - all data that is identifying - unique to the tab. So you couldn’t open a second tab and remain logged in to your bank account, for example. the urls are examples; I’m on my phone, not on my laptop.

d6de964 9y ago
Can't the websites share that information with facebook by proxying that information? It'd be the same workaround as for ads if you host them it's very hard for someone else to block them, especially if you use dynamically named divs, image sizes etc.
- dfee 9y ago
  No. You’re not providing your Facebook cookie to the third party site. So, there is no way to associate your identity on example.com with your Facebook profile. Think of it this way, if you have an authentication ticket, such as what is in a session cookie, then you have access to your account. If someone intercepted that ticket / cookie, they could maliciously act on your behalf and play around on your Facebook - just like you. Your browser therefore doesn’t send cookies to domains that aren’t specified as trusted by the originator of the cookie; I.e. third parties. So example.com and Facebook wouldn’t be able to associate the two identities. *except of course through some interesting trickery like browser fingerprinting.

by dfee 9y ago

d6de964 9y ago

Can't the websites share that information with facebook by proxying that information? It'd be the same workaround as for ads if you host them it's very hard for someone else to block them, especially if you use dynamically named divs, image sizes etc.

dfee 9y ago
No. You’re not providing your Facebook cookie to the third party site. So, there is no way to associate your identity on example.com with your Facebook profile. Think of it this way, if you have an authentication ticket, such as what is in a session cookie, then you have access to your account. If someone intercepted that ticket / cookie, they could maliciously act on your behalf and play around on your Facebook - just like you. Your browser therefore doesn’t send cookies to domains that aren’t specified as trusted by the originator of the cookie; I.e. third parties. So example.com and Facebook wouldn’t be able to associate the two identities. *except of course through some interesting trickery like browser fingerprinting.