The
Internet: A Brief History
The
Internet was originally designed by the US Department of Defence
as a 'resilient' communication system, which could resist attack
on communication nodes. Previously, systems relied on one central
computer to send information to others. The Internet (then called
ARPANet, for Advanced Research Projects Agency Network) used 'peer-to-peer'
networking - a series of computers where each machine had responsibility
for checking the network and its communications.
Since
the early 1980s, when it was used predominantly by academics and
scientists, the growth of the Internet has been exponential -
over 30 million users in 1995. The Internet has been called a
'network of networks' - the term Internet covers hundreds of smaller
localised networks which can be connected using it.
The
Internet operates in a similar way to the telephone network, and
uses much of the existing cabling. The major difference is: with
voice signals, while you talk, one circuit or phone line is exclusively
used for that call (called 'circuit switching'). When computers
communicate, they use a 'packet switching' procedure, sending
small 'packets' of data through the network.
In
effect, this means no single computer has a monopoly over phone
line usage, the lines being 'multiplexed' - any number of packets
can be sent at the same time. Each packet has its destination
address included in it, and is sequentially numbered. In this
way, they can be sent in any order and reassembled at the other
end. It also means that information can be sent via a variety
of paths to get to the same destination.
This
works because all computers connected to the Net speak the same
type of language - TCP/IP, or Transmission Control Protocol/Internet
Protocol. TCP regulates how the computers talk to each other and
share information; IP regulates the addresses of computers. This
also allows different types of computer to interact. For example,
a message typed in on an Apple or PC could be read by a UNIX mainframe
computer and vice versa.
The
arrangement between the machines is often called Client/Server.
The Server is the machine sending the information, the Client
is the machine receiving the information.
Another
term used is Local/Remote Host. The 'local' machine is yours (or
the service provider's); the 'remote' host is the one connected
to its service. This allows you to access directories, programs
and software on the 'remote' machine.
File
Transfer Protocol, or FTP is the most common method for transferring
information on the Internet. It refers to two different items:
The communication protocol (a standard way for computers to talk
to each other) and the actual software used to transfer files.
Contents:
World Wide Web
Skill
Check: World Wide Web
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