About the Internet
The Internet is a network of computer networks, stretching around the world. Over 23 million people use the Internet to find information, to conduct business, to communicate with people around the world, and to play games - and more and more of us are discovering it every day.
Information can be sent and shared on the Internet in many ways. Some of the most popular are:
- Email - Send mail around the world in minutes. Correspond with your friends, or join a mailing list discussion.
- The World Wide Web - Point and click to move between "pages" of information and graphics. You're reading a Web page right now.
- Usenet News - Subscribe to up to 14,000 discussion groups on topics from fish-breeding to the latest JFK conspiracy theories.
- FTP - Download files, programs and graphics from public archives.
- IRC - Chat real-time with other users.
- Telnet - Connect directly to other machines on the Internet.
- Gopher - The grandfather of the WWW. Use menus to navigate your way to information.
So what's the big deal? What makes the Internet different from "online services", TV networks and all the other data that surrounds us every day? First, there's no limit to what you can find on the Internet. When you read a newspaper, watch TV or listen to the radio, you see and hear small "bites" of information someone selected for you. Even when you log on to an online service, you can only find the news, entertainment, and discussions that service chooses to offer you - unless it has a gateway to the Internet. From the page you're reading right now, you can get to any information that one of your 23 million fellow users decided to make available, anywhere in the world. And that's the second thing that makes the Internet unique -*any* user can contribute. Whether you decide to join the Electronic Frontier Foundation, publish your novel online, or just submit a new joke to rec.humor.funny, what you do can affect the shape of the Net community.
Who Owns the Internet?
No one person or agency owns the Internet. Instead, thousands of regional networks and providers, pass information through each other and over a few central "backbones". These backbones may be owned by goverment agencies (like the NSF) or by telecommunications companies.
The U.S. telephone system is one good analogy for the way the Internet works. You probably have at least one phone number in your residence; you lease that phone number from your local company, sometimes with added services like call waiting.
When you make a local phone call, the things you say and hear travel over your phone company's regional network. If you call a number in another state, your conversation is passed from your phone company's network to the network of a long-distance provider. This long-distance telecommunications "backbone" takes your call across the country, to the local phone company network in the place you are calling.
The Internet operates in the same way, with two exceptions. First, you don't have to pay extra to send Internet information "long distance"; your local provider builds their own backbone or leases one from another company. So you can spend your online hours connected to Japan or the computer next door, for the same monthly fee.
Second, anyone can set up their own network connection to the Internet, or even their own network. Most colleges and universities provide some Internet access to students, and many companies have at least an email gateway to the Net. There may even be a public-access "Freenet" in your area.
How is the Internet Administered?
Just as no one owns the whole Internet, no single agency determines how it operates from day to day. Here are a few of the most important organizations involved:
The National Science Foundation (NSF) has been instrumental in shaping the current form of the Internet, especially its educational and noncommercial culture. Right now, various commercial investors are taking over the major network "backbones", and the NSF is turning its attention to other areas of computing.
The Internet Network Information Center(InterNIC), which is sponsored by the NSF, assigns and registers an IP address (see "How does it All work?") for each U.S. computer connected to the Internet. They also maintain public databases anyone can use to look up users and computers on the Internet.
The Internet Society(ISOC) and the Internet Engineering Task Force(IETF) help to develop the protocols that determine how the Internet works. Established protocols are known as RFCs; some must be used by all sites, and some are just guidelines, proposals or comments. For example, RFC 822 established the format of the headers you see in every Internet email message.
Each Internet provider or site decides what its users may do on the Internet, what standards it will comply with, and what kind of information it will receive from and transmit to the world. There is no governing body which enforces formal laws; instead, the RFCs serve as technical conventions, and Netiquette defines the rules of behavior users should follow. Providers and users who ignore these guidelines may find themselves shunned by the rest of the Internet community.
How Does the Internet Work?
Information is transmitted over the Internet in the form of packets. When you send a piece of information to another user or computer on the Internet, the application you're using (email, telnet, or whatever) breaks it down into packets of a certain length and sends it out. Each packet gets handed along the net by computers that have been designated as routers, until it reaches its destination machine. There, the packets are reassembled into the piece of information and sent to the appropriate user.
As an example, let's follow the delivery of a single email message sent by a person with the account user@znet.net to the address student@BigU.edu. Our sender writes the message, addresses it and clicks the "Send" button.
The mail server acts like a local U.S. Post Office. It receives each packet in our message and checks the address. If this were a mail message to another Simply Internet user, the mail server would send it straight to their mailbox. But it's not; so the server checks its records for the nearest router which might know where BigU is, and sends the packets them off.
Every site on the Internet has at least one router, which knows something about the sites and networks around it. The packets of our mail message are passed from one router to another until it reaches one that knows exactly where BigU's computers are.
Because each router has only a partial "roadmap", packets may not always take the most efficient path to their destination; a message may travel across the country and back to reach a computer only a few miles away. In addition, packets can take many different paths to get from one place to another. So the packets of our mail message probably arrive at BigU from different places and at different times, even though they all left Simply Internet at once.
The mail server at BigU waits until all the packets have arrived, assembles them back into the email message, and stores it in the mailbox belonging to the account "student". The whole process may have taken from minutes to hours. If the BigU mail server can't deliver the message for some reason, it will return it to user@znet.net, with an error message.
The protocol used to transfer packets across the Internet is called Internet Protocol, and the protocol that breaks information into packets and reassembles it is Transmission Control Protocol. You'll usually see them referred to as TCP/IP.
Internet Names
Computers refer to each other by their Internet Protocol or IP addresses. Each computer connected to the Internet is assigned an IP address made up of four numbers, separated by periods. The structure of IP addresses is too complex to go into here. Domain Name System, or DNS, turns these numbers into addresses that humans can remember. Domain name addresses have several parts. Let's take two examples:
The rightmost part of an address is its top-level domain. This is determined by the nature of the site. Simply Internet is an Internet Service Provider, so its domain name ends with "net". BigU is a college or university, so its name ends in "edu". Addresses outside the U.S. usually have a country code as a top-level domain.
The next section of an address is usually the main domain name at that site (simplyweb, csusm). The section on the far left (iago, sm) is the name of a specific host (computer) at that site. Some Internet addresses include the names of one or more networks between the host and the main domain name; the "sm" in the second example probably stands for the San Marcos campus of csusm.edu
Both top-level domains and main domain names are assigned and administered by the InterNIC. Each site is responsible for taking care of all the networks and hosts inside it, and making sure no two computers ever have the same address. Computers on the Internet translate between IP addresses and domain name addresses in the same way they deliver packets - they ask each other in turn until someone knows the answer. Each site has a domain name server that may know the names for some addresses, and some other servers it can ask to look up the rest. If no domain name server on the Internet knows the domain name for a site, you won't be able to reach it by its name.
Types of Internet Connections
There are several types of Internet access. The simplest (and usually the cheapest) is to get an account on a machine that's permanently connected to the Net. Your "host" machine takes care of system chores like delivering your mail and news, and provides you with a number of programs you can use. All you have to do is call the machine with a modem and a communications program. Simply Internet's Unix shell accounts are an example of a "host" connection.
Host accounts are fast, reliable, and can be very flexible and powerful if you know what you're doing. The catch? In order to use them, you have to learn the commands for your host system (Unix, or possibly VAX). They're text-only, which means you can't view graphics on the WWW. (Note: It's not possible to run a SLIP emulator program which converts a host connection to a network connection, allowing host users to run Netscape and other browsers.) And you can only use the programs which your host computer provides.
The next type of Internet access is a dial-up network connection. You use a modem and networking software to dial a host which is connected to the Internet, and the host assigns you a temporary or permanent IP address. Your host still provides mail and news to your account, but you configure and run your own applications to read them. Dial-up network accounts are easy to use, and allow you to download information and graphics to your PC much more quickly than a simple host account. You can only transfer data as fast as your modem and your provider's modem allow, however (usually 28,800 baud or slower).
At the top of the Internet ladder are UUCP and the different types of high-speed permanent network connections. Companies, governments and other organizations use these to provide Internet access for their members. Network and UUCP accounts can have their own Internet domain names, and are partly responsible for administering their own email and news.
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