Get a domain name
Instead of writing your public IP, someone might want to reach your serveur using something more human friendly : a domain name.
What is a domain name ?
One can register a domain, i.e. "something-cool.tld" as a sign pointing to your IP address. When an human enter "something-cool.tld", the computer will ask the registrar what IP is behing this sign to reach this. In this case, the domain is resolved.
It is easier to remember, it gives identity to your project, ans it let you organise it using subdomains (webmail.athome.tld, cloud.athome.tld...).
You can find free registrar, or rent a domain name. There are many registrars out there. I've been happy with there ones, especially GANDI because it's self-hosting friendly :GANDI (20% off with this referal link)