Domain names are alphabetic and easier to remember than numbers.
The Internet however, is really based on IP addresses, which are numbers. For every domain name request, a DNS service must translate the name into the corresponding IP address. For example a domain name of servername.edu could be translated to an IP address of 146.7.22.10. If the first DNS server cannot process the translation request, it queries an upstream DNS server, and another one, and so on, until the correct IP address is returned or no corresponding address for the request can be found.