What is a domain name?

When most people think of DNS, the Domain Name System, they think of a very specific use case. You want to visit a website and in order to do so, you have to connect to its IP address. But IP addresses are hard to remember. Names, however, are easy to remember. So, DNS creates a mapping between an easy to remember the name and a hard to remember IP address. A domain name is just a list of labels separated by dots, but the labels are not arbitrary, they're organized into a tree structure which should be scalable.