APPENDIX A: The Internet - How it works and where it came from
History of the Internet
So how did it all start? The forerunner of the present Internet was
a US Department of Defence network in the 1960s known as the ARPAnet. This
was a network of computers located throughout the whole of the US and linked
by phone lines. The original intention was a system where research information
could be sent even if some of the computers on the network were not working.
When it was realised that a system like this would be difficult to knock
out in the event of nuclear war, the US military began to look at its further
development.
Throughout the 1970s, the ARPAnet continued to expand. ARPAnet was also
used by the main Universities for research purposes. In the early 1980s,
small groups of enthusiasts also developed small networks. It was not until
the National Science Foundation Network (NSFnet) was set up, that the concept
of interlinked computers became popular. This brought together the five
NSF "supercomputers" along with local and University networks.
As more Universities and regional networks joined the system, it began
to get overloaded. The network underwent a major overhaul in 1987 with
the help of IBM, MCI, and Merit computer companies. The improved network
could now accommodate links to many smaller networks in the US, Europe,
and Japan. This worldwide network became known as the Internet.
However, the Internet in the late 1980s was still text based and not
a very exciting or easy place to navigate through. In the early 1990s this
all changed when scientists at The European Laboratory for Particle Research
(known as CERN) invented the World Wide Web. They wanted to make it easier
for their scientists to share information on the Web. They solved their
dilemma by inventing HyperText Markup Language (HTML). Now the Internet
was able to support pictures and nicely formatted text but more importantly
it contained hypertext links. This development brought the Internet out
of the backwaters of academia into the homes and lives of ordinary citizens.
Since 1988, the Net has doubled in size each year, and this growth is accelerating.
As more services become available, the Net will play a greater role in
all of our lives.
How the Internet works
The Internet is basically millions of computers connected together by
phone lines. The term "cyberspace" is commonly used to describe
the Net concept, as there is no tangible machine or computer that you can
point to and say "That's the Internet!". The nearest you will
get to doing this is to point to the high capacity cables that form the
backbone of the Internet. From these lines, there are smaller capacity
lines which are leased by the Internet Service Providers. They in turn
provide access to their customers through the ordinary telephone network.
Protocols
As the Internet is made up of many different networks and computers, there has to be a system or protocol which allows all these computers to communicate with one another.
Protocols are simply methods used by computers to communicate with each
other. With such a large number of computers and networks, phone lines
and cables, how can we be sure that data is transmitted along the correct
phone lines to the right computer? The following protocols are the ones
that you are most likely to come across:
FTP: File Transfer Protocol is used to move files between computers
on the Internet.
PPP: Point to Point Protocol allows a computer to use the Internet with
a standard telephone line and modem.
SLIP: Serial Line Internet Protocol . Serves the same function as PPP,
but is an older protocol.
TCP/IP: Transmission Control Protocol/Internet Protocol allows data
to be transmitted over the Internet in an orderly fashion. TCP breaks up
the data into related pieces of information and then puts them all back
together in the correct order once they reach their destination.
Most individuals use their modem and computer to dial up and connect
to the Internet but this is not the only option. No matter how fast your
modem is you are still sending and receiving information over the phone
line and this can be slow. You will notice when you are on-line that Web
pages take time to load on the screen, text first, then images. The faster
your modem, the quicker this will occur but there are other options.
The Internet has been referred to as the Information Superhighway, but
if you have a slow connection it's more like being stuck in traffic on
a slip road - very frustrating. When you are accessing Web pages that contain
graphics, movie clips, and sound files, you will need a lot of bandwidth
or else you will experience this frustration.
Bandwidth
Bandwidth refers to the amount of information that can travel along a cable and is measured in bits per second. The more bandwidth you have, the more data that can pass through the network at once. If you have more bandwidth, more students and teachers can go on-line at the same time. Using a modem and a dial-up connection is great for a single user but if you have your entire class on-line together you need a direct connection to the Internet. Such "dedicated" or "direct" connections are more expensive than ordinary phone lines, as digital rather than analogue phone lines have a larger bandwidth.
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