Pi-Hole

the infinite dns sinkhole.

DNS is very very complicated. Actually, no it's not. Basically DNS maps IP addresses to domain names. e.g. 1.1.1.1 to Cloudflare.com or something. Every conceivable service on the Internet most likely has a domain name (the DN part of DNS, for Domain Name Service) for simplicity's sake.

However, if we want to run our own services at home, we don't really want to memorize allat. That's why we have a DNS server. To have devices on our home network recognize custom domain names. Also, please make sure to use a TLD that isn't routable across the internet, like .home or .box.