Here is the original Cloudflare post on what 1.1.1.1 is [1]. For those who don't know, 1.1.1.1 is Cloudflare's privacy focused DNS service. That means that when you type in www.google.com, that URL can be sent to 1.1.1.1, and then 1.1.1.1 resolves that URL an IP address and send the IP back to the user. All user requests are then sent to the IP address, not the URL. Supposedly this is better than using the DNS server of ATT+Comcast, because ATT+Comcast want your browsing history while Cloudflare does not.
What I don't understand is how this really helps user privacy much. If AT&T, Comcast, etc want to know your browsing habits, can't they still see the IP addresses you're browsing and figure out the URL from the IPs? I can't see that as too big an impediment, but maybe someone with more knowledge can share.