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INTERNET The word “internet” is short for INTERCONNECTED
NETWORK. The Internet is a
specific worldwide collection of networks. A large collection of computers
all over the world - connected together.
Using e-mail on the Internet, you can communicate with people
throughout the world. “E-mail” is
short for “ELECTRONIC MAIL” WORLD WIDE WEB is
the part of the Internet where the computers are connected in a specific way
that makes those computers and their contents accessible to all the other
connected computers. COMPUTER NETWORKS –
The computers in the computer lab are connected to each other by inserting a network interface card into each
computer and then connecting cables from each card to the lab’s SERVER. The
Server accepts requests from other computers connected to it and shares
resources such as printers, files and programs. This is called a CLIENT/SERVER
NETWORK. The special software is called a NETWORK OPERATING SYSTEM. HOW THE INTERNET BEGAN: During the 1960s, the Department of
Defense became concerned about the possible effects of nuclear attack. It
realized that the weapons of the future would require powerful computers for
coordination and control. The DOD created a network of networks.
It is designed to look like a spider so that if any node on the network was
destroyed, data could be routed through a different channel. Because the computers during the 1960s
were all large mainframe, the task was enormous. The DOD had to examine
various ways to connect these computers to each other - and to all the weapons installations
around the world. The agency in the Department charged
with this task was the ADVANCED RESEARCH PROJECTS AGENCY. Referred to as both ARPA and DARPA.
The agency hired the best communications technology researchers and funded
research at leading universities. Initially, the networked computers were
linked over telephone lines. Once the connection was established, the data
traveled along that single path and the telephone company’s central switching
system selected specific telephone lines (circuits) that would create the
single path. This centrally controlled, single-connection method is called CIRCUIT
SWITCHING. DARPA used PACKET SWITCHING. In
a packet switching network, files and messages are broken down into packets
that are labeled electronically with codes indicating their origin and
destination. The packets travel from computer to computer until they reach
their destination. The destination computer reassembles the data. Each
computer that a packet encounters on its trip through the network determines
the best way to move the packet forward to its destination. The computers
along the way are called ROUTERS. In 1969, DARPA connected the first
computer switches at the PROTOCOL is
a collection of rules for formatting, ordering, and error-checking data in a
network. INTERNET PROTOCOL (IP)
ensures that all computers on the network will be able to communicate with
each other – regardless of their brand name or operating system.
(Transparency) TRANSMISSION CONTROL PROTOCOL (TCP)
converts messages into streams of packets and reassembles them. This is
similar to sending a letter that gets cut up into little pieces when you mail
it, each piece traveling a different route, and yet arriving at its address
whole. In 1972 a program was written that
could send and receive messages over the network. E-MAIL was born and grew
quickly. FILE TRANSFER PROTOCOL (FTP)
allowed users to transfer files between computers, and TELNET let users log
in to their computer accounts from remote sites. The first e-mail mailing
lists also appeared on these networks. This was not e-mail as we know it
today... (A MAILING LIST is an e-mail address that takes any message it
receives and forwards it to any user who has subscribed to the list.) In 1979, a group of students and
programmers at Researchers at the |