So we've seen that people refer to computers using names and computers refer to each other using numbers. The system for doing these translations is DNS, the Domain Name Service, which is run by computers called nameservers. DNS resolves names into numbers. It also reverse-resolves numbers into names, so your computer can tell you the name of a computer it's talking to. Summary The main points are Computers use numbers to refer to each other.
People prefer to use names.
Domains are a way of naming computers. The Web is only one of many uses for computers named this way. It is if you're thinking of getting a domain name for your website. However, domains are a way of naming computers, not websites. If your website is the only website on a computer, it doesn't matter whether you think of the name as applying to the computer or to the website.