A Domain Name Server (DNS) is a Server that controls the flow of traffic around the internet. It’s like an address book that says the URL you are looking for (e.g. google.com) is located at this IP address (xxx.xxx.xxx.xxx).
Think of it like Mindy and Mike’s Gym in the Hello Yellow is located at 1 Real World Road, Real World, Real Country 112233. Each DNS Server only holds a part of the internet’s address book, so the communication looks more like around 5 or more of these DNS Servers saying … Mike and Mindy’s gym isn’t here, but try the DNS Server over there and they may know. The information could bounce around anywhere in the world to find its destination over the internet.
Adapted from Ernst (2013)