Web Environment Integrity API, an API that will gather metadata about your system setup, hardware and software, as well as if you have any extensions installed. Only WEI compliant browsers will be able to view WEI compliant webpages.
I don't know how this works, but in simple terms, when the server asks the Infos from the browser, can't the browser just lie? I don't understand why this is such a big deal, or am I missing something?