A friend recently asked me what the internet was. Evidently there are some strange theories floating around out there, such as the one Jon Stewart mocks in this clip:
So I gave her an explanation and she said she thought some other non-technical friends might appreciate it, so here it is.
Your computer has a few key components — a CPU, a hard drive, RAM, and an Operating System. Everything on your computer is completely obedient to your Operating System.
If you have two or more computers in your house, you can set up a network between them. When you set up a network, you’re basically adding additional components to your computer. But these additional components are obedient to different Operating Systems than your own.
So your Operating System has to ask the other computer’s Operating System for permission before it does anything like read a file from the other computer’s hard drive.
To set up a network, you need to tell the computers two ground rules: what “language” to speak with one another and how to find other computers on the network.
The Internet is the largest network of computers ever created. There is a standard language (TCP/IP) and a standard way to find other computers (the unique IP address that every computer on the internet is assigned).
Whenever you log in to a wireless network, for example, you are assigned a temporary IP address that any computer on the internet could use to talk to you. Permanently-connected computers such as webservers get permanent IP addresses.
So when we talk about the internet, we’re really talking about every computer in the world that has a legimitate IP address and knows how to talk to other computers using TCP/IP.
As a language, TCP/IP is too generic to be useful for most of the tasks we are interested in. So there are additional dialacts called “protocols” which computers can use to do things like view web pages.
To view web pages, computers talk using HTTP — Hyper Text Transfer Protocol. That’s what the http:// in front of a web address is all about. To upload or download files computers use FTP — File Transfer Protocol.
There are a lot of different protocols.
So when you type http://news.google.com/index.html into your browser address bar, what’s really happening is that your Operating System connects to the Internet using TCP/IP and asks a more significant computer what the IP address of news.google.com is.
Then it uses HTTP to talk to the Operating System of the computer at that IP address and asks for permission to read the file index.html. The remote Operating System uses HTTP to answer “Sure” and then passes the file along. Your computer then displays the file in your browser.
And that’s essentially what the internet is and how it works.