For those who are referencing tracking pixels and say this isn't anything new, it's important to understand that this is the next evolution of that technology as a result of government regulations around privacy and browser/OS ecosystem changes from Google, Apple, and Mozilla. This data transfer won't occur at the browser layer for much longer - it won't be as technically feasible without cookies and it may not be legal given consent/opt-out requirements. Instead the data will pass directly from the advertiser's server to the ad platform's server. Of course this tech has existed for a long time - it's a basic API call - but it hasn't been widely adopted in the ad tech industry, while millions of websites are using tracking pixels.<p>It is not a 1:1 replacement for tracking pixels and lacks some of those creepy features (you're unlikely to get tagged if you simply browse a website without giving up any personal info), but it offers new ones as well (the ability to send arbitrary data to an ad platform).