How the Internet Works
Your Computer
If you were in your house, but you needed to get a few things you would assign different tasks to your good for nothing housemates. So let's say you need to get eggs.
You would give your daughter money, who would then give it to your wife (who you aren't fighting with....it's just you hate her face).
Your wife, would give the money to your son, who would go buy eggs,
and use the change to buy beer. He would give the eggs to his mother,
who would give it to your daughter, and then you could throw the
eggs at your wife's car.
That is how the internet works!
Your computer sends a signal down the TCP/IP protocol stack. The signal goes from an application (your daughter) to the IP (your wife), down to the hardware layer (your son). The hardware layer breaks messages into binary and, if the messages are too large, into packets. Before we talk about where the packets go, let's talk about how your computer deals with packets.
When your computer recieves packets, the hardware layer converts them from binary. It organizes this information and sends it to the IP layer. The IP then sends the information to the application, which handles the readability for you.
NSPs and ISPs
In order to get the eggs, your son had to drive on roads. These roads may be owned by California, a private citizen, or whomever. And on his way he may have to take several different roads, made and owned by different people. This, in essence, is an NSP.
NSPs (Network Service Providers) make up the backbone of the internet, which are required connect to Network Access Points (NAPs). When your packets reach an NAP, they may jump from one access point to another. Metropolitan Area Exchanges (MAEs), are like Network Access Points, but are privately owned. These two (NAPs and MAEs) make up Internet Exchange Points (IXs).
NSPs sell bandwith to Internet Service Providers (ISPs). You have dealt with an ISP, as they are the ones who provide you access to the internet. So in essence, your ISP acts as a bully who stands outside your door, demanding a toll monthly so your son can buy eggs.
Looking for your Information
Now, let's say that your mom told your son to go to a specific market, like Safeway on the corner of 40th and Buena Vista. If your son didn't know how to get there, and he didn't have GPS, he may call a friend. If the friend didn't know, he could call someone else, until someone gave him directions.
This is how your computer finds your information. Your packets are sent to a router. The router looks to see if it knows where the IP address you are looking for is. If it does not, it asks another router, going up a chain, which will eventually stop at the NSP backbone.
It gets slightly more complicated, since the name you use to find a website, and the one your computer is looking for is slightly different. You go to www.SadandUgly.com, but your computer looks for an IP address. The router your computer asks is called a Domain Name Service.
SadandUgly.com is known as a Uniform Resource Locator (URL), but the IP address is a series of numbers, and in order to retreive that information, your computer has to ask the DNS where the site is located.
A domain name service is a database (a list, if you want), which tracks different IP addresses. But, it cannot hold all of the IP addresses to the entire internet.
Other Pertinent Information
As you may, or may not know, there are many programming languages. Like English, Spanish, and other langauges, those languages have rules, which people choose to follow, or not. When your computer looks for a website, it requests this in HTTP protocol, which is not to be confused with HTML.
HTML is Hyper Text Markup Language, which is how programmers present information on a webpage. HTTP is a protocol which determines how computers communicate over the world wide web, WWW. When you type a url into a page, you ping a DNS server, retrieves the data, and your computer parses it.
Putting it all together
When your computer gets information from a website, it goes down the TCP/IP stack, which sends packets through your ISPs routers. It goes through these routers, using the DNS, until it finds a web server. The web server responds with some HTTP, and your computer goes back up the TCP/IP stack to serve you the information. If that doesn't make sense, go back and re-read this page.