I'll assume the second.
Explain that the internet is just a collection of computers that are connected to each other. Some computers are always on and hold websites (servers) so that other computers (say, typical PCs) can connect to them to see the websites.
Now there are some computers that have the job of acting as the phone book so that the other computers know where to find the servers.
I like this exercise. It forces yourself to explain a system in the most simple terms possible.