Privacy Relay is built into both the forthcoming iOS and MacOS versions, but it will only work if you’re an iCloud Plus subscriber and you have it enabled from within your iCloud settings.
Once it’s enabled and you open Safari to browse, Private Relay splits up two pieces of information that — when delivered to websites together as normal — could quickly identify you. Those are your IP address (who and exactly where you are) and your DNS request (the address of the website you want, in numeric form).
Once the two pieces of information are split, Private Relay encrypts your DNS request and sends both the IP address and now-encrypted DNS request to an Apple proxy server. This is the first of two stops your traffic will make before you see a website. At this point, Apple has already handed over the encryption keys to the third party running the second of the two stops, so Apple can’t see what website you’re trying to access with your encrypted DNS request. All Apple can see is your IP address.
Although it has received both your IP address and encrypted DNS request, Apple’s server doesn’t send your original IP address to the second stop. Instead, it gives you an anonymous IP address that is approximately associated with your general region or city.
Read more: schneier.com