The internet
The internet is a constantly evolving system. When I say internet, I mean the global network of cables, Internet Service Providers (ISPs), routers, switches, and computers that let all of us communicate. There are cables on poles, underground, underwater, hanging between buildings, inside buildings, and really anywhere you can shove a cable.
Figure 1: A map of all submarine cables from submarinecablemap.com in 2018
Some countries have one ISP, while others have hundreds. In some countries, the government owns the cables, while in others they are owned by private businesses. Many places do not have any cables and receive all of their internet via wireless from long-distance towers or from satellites.
Often, when people try to draw a graph to describe the internet, they draw something looking like a complete bipartite graph, where every node connects to every other node. Instead, it's more like a city sewer system—lots of trees and graphs connecting to large pipes that...
