As I understand it today, I can view an ad on a random site and have a cookie with my unique ID in it saved. If I view other network ads, they know it's me and update my profile. Then when I check out, the site I'm buying from reads this cookie and reports back that it worked based on impressions.
AFAIK this won't be easy to replace if a random eCommerce store is blocked from reading Facebook et al cookies, it won't be able to report back reliably. You could do something like submit their email address or other data to Facebook and see if you get a hit, but that's probably illegal in many places without permission. And in most cases, the cookie from the ads will be blocked as it's third party (but would be able to be written for ads shown on-platform, which doesn't really matter since they can track server side anyway).
But clicks are very easy, you just tie a unique ID to the ad URL and have the landing page and checkout page track that. No cookies needed. It can report back in real time or later to update stats.
Minor point but the e-commerce site will not be able to read the cookie from Facebook - it will have a special code snippet on the "thank for your purchase" page. When your browser loads this page it also loads the snippet from Facebook (could be a 1x1 pixel or iframe etc etc) and your browser dutifully passes on the cookie as usual to facebook.com when it loads that snippet (i.e. facebook.com is the third party host) then Facebook's servers log the http request with the cookie ID so they mark that as a successful "conversion" (aka sale).
The browser will not make cookies from other sites available to the e-commerce site. There is no chance for the e-commerce site to take a look at what is in the Facebook cookie
Yeah true,and thanks for that. I unintentionally oversimplified.
I meant the 'page' (including the FB pixel JS on it) could read the pixel but the problem is of course the page is composed of resources from multiple domains and parties.
I'm pretty sure these days the default is just a JS ping to an endpoint, but the eponymous pixel exists under noscript tags for legacy support.
As I understand it today, I can view an ad on a random site and have a cookie with my unique ID in it saved. If I view other network ads, they know it's me and update my profile. Then when I check out, the site I'm buying from reads this cookie and reports back that it worked based on impressions.
AFAIK this won't be easy to replace if a random eCommerce store is blocked from reading Facebook et al cookies, it won't be able to report back reliably. You could do something like submit their email address or other data to Facebook and see if you get a hit, but that's probably illegal in many places without permission. And in most cases, the cookie from the ads will be blocked as it's third party (but would be able to be written for ads shown on-platform, which doesn't really matter since they can track server side anyway).
But clicks are very easy, you just tie a unique ID to the ad URL and have the landing page and checkout page track that. No cookies needed. It can report back in real time or later to update stats.