What Is The Internet?

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.