The Internet was designed as a loose interconnection of nodes (computers) that can be added in an un-coordinated way, provided they all communicated using the IP protocol and following the standardised addressing scheme. Because the addition is not coordinated and the links (both physical and logical) among the various nodes are dynamic, it has become more and more difficult to map the internet. Besides, whatever map you may come up, it will be valid for a specific moment and even for that moment it will represent just a partial view.
If I send an email from my computer to you and you look at the header of the received mail (depending on the mail app you are using you have different ways to display the header. If you have, as I do, the Mail app on an Apple device you need to click on View > Message > All Headers) you can follow the “path” taken by that message to get from the sender to you. You’ll discover that the path has taken the message across tens of computers (servers) to finally reach you. You will also discover by looking at other messages from that very same sender that the paths change over time. This is the nature of connectivity on Internet.
I remember, long time ago, in 1975, learning the “hot potato” routing algorithm, originating in military communications and inherited as a concept- by Internet: you send a message through all paths that you have available and all receivers will do the same. The message “header” keeps track of the path followed and once, by chance, it reaches its intended destination it will have the record of the “route” followed. Several copies of that message will finally get to the destination (by pure chance) and the destination point by looking at the various routes can identify the most effective one and send back this info to the sender so that from that moment on all messages from that sender to this receiver will follow that path (and get acknowledged). If something goes wrong (a broken link) the sender will not get an ack and it will start the hot potato procedure all over again (the idea of the “hot potato” was that if you are catching a hot potato you will through it away immediately with no particular aim, just to get rid of it). Over the years the strategies have become more sophisticated but at the core they are still like that. This is why the internet is so resilient!
Researchers from time to time work out some software to trace the connectivity on the Internet and render that into a graphic. As I said, this is just a snapshot, it keeps changing. Nevertheless it provides an idea of the overall structure (the image in the figure was created in 2007 by MIT researchers using as tracers tens of thousands of originating points).
Because of its continuous growth, it would be nice to appreciate how it changes over time. This is what is shown in the clip below, tracking the evolution from 1997 up to January 2021: enjoy!
White = Backbone
Blue = North America
Red = Asia Pacific
Yellow = Africa
Green = Europe