This starts to sound kind of Zen, but the internet is everything, and the internet is nothing.

There is no single thing I can point to and say "this, this thing right here that your ISP connects to, that is the internet". It just doesn't work that way.

If we look at it differently, your ISP is the internet. When you connect to your service provider, you are connecting to the internet right there.

Think about it -- if you send email to a friend of yours that uses the same service provider that you do, that email goes from your machine to the service provider to your friends machine. It never had to go anywhere else that your service provider might be connected to, and still, it did go over the internet - your service provider's little corner of the internet.

The internet isn't really a thing that ISPs hook up to. It's more like a side effect of the fact that all the ISPs are connecting to each other in various and fairly random ways.

Now, in the case of a small ISP, they may get their connectivity to the rest of the internet by purchasing a connection from a larger ISP. Typically it's an extremely high speed or high bandwidth connection. A good ISP will connect to the rest of the internet using more than one such connection, from more than one provider, to balance the load, and provide fault tolerance should one of the connections drop.

"The internet isn't really a thing that ISPs hook up to. It's more like a side effect of the fact that all the ISPs are connecting to each other in various and fairly random ways."

Larger ISPs, such as AOL, earthlink and others may not have a need to connect to an upstream ISP, since that's already them. Instead, the larger ISP's negotiate connectivity between themselves. This allows you, through your little ISP to get connectivity to everyone that your ISP, and your ISP's ISP, (and perhaps your ISP's ISP's ISP, and so on) can connect to.

The point is simply that there's no central point.

One of the reasons the word "web" is so appropriate in World Wide Web is because that's a much more accurate picture of how things interconnect. Between any two points on a spider web, there are hundreds if not thousands of ways to get from point A to point B. The internet works (roughly) the same way.

So, could you connect directly to whomever your ISP connects to? Probably. In fact, that's what many large corporations do ... they skip the low level ISPs completely and purchase bandwidth in bulk from larger service providers. You could do that to, provided you were willing to spend the money to do so, and have the technical ability to set up your side of the connectivity. It's rare that the upstream network providers are set up to also deal with single user / home / small business connectivity.