I have often wondered how the Internet works. The core technology, TCP/IP, is well understood, but the question is how data gets from one place to another. That is, if I send an email to from my Earthlink account, how does it get to your account at Yahoo!. How does the data actually travel? The short answer is that there are two ways that networks interconnect. The first is called "peering" and the second is called "transit". This article discusses these two concepts and how networks together to allow data to move from one to another.
This article is a bit technical, but interesting nonetheless.