URL stands for Universal Resource Locator.
It’s the entry in the registry that connects your payment account to the ownership of a ‘domain name’. All domain names are owned by proxy by a registrar. This is why you go to a “registrar” to purchase a domain name – not your host. Some hosts also function as registrars so it can be confusing.
It’s the responsibility of the registrar to connect your URL with the IP address of your hosting company through a setting called “DNS”. It’s really not worth remembering what all those letters stand for because you will never hear anyone refer to them by their full English names.
WARNING: if you have a URL that is connected to a business, or you have just spent a lot of time building it up, always put it on auto-renew. If you let it expire, the danger isn’t from domain poachers that are lurking to snatch it up, but from the registrars themselves. They keep possession of the names for about 30-60 days offering you a ‘second chance’ to get your name back. The second chance often comes at an incredibly inflated price (a $12 renewal turns into a $250 purchase). Be warned!