Chapter 1

The Internet

The internet is a worldwide network of computers with the property that each

computer can send data to and receive data from any other computer on the

internet.

1.1

A brief history of the internet

The idea of connecting computers via phone lines or some other long distance

network was first tested in 1965 when two university researchers, Larry Roberts

and Thomas Merrill, connected a computer in Massachusetts with one in Cali 

fornia using a phone line and demonstrated that they coould run programs and

receive data on the remote machines. A key idea behind this research was that

the computers would communicate by breaking up their data into many small

packets and sending these packets individually. If any packets were lost (due to

background noise on the line), they could easily be resent.

This experiment led directly to a DARPA (Defense Advanced Research

Projects Agency) proposal in 1967 to build the ARPANET, which is a mili 

tary precursor of the internet. In 1968 a group led by Frank Heart at BBN in

Boston won the government contract to build the initial ARPANET hardware.

In 1969, the initial ARPANET was constructed and consisted of four comput 

ers: three in California and one in Utah. In 1972, Roberts wrote the first email

program, and email quickly became the most frequently used network applica 

tion. In 1973, Vint Cerf and Robert Kahn proposed a new set of communication

rules for the computer networks called TCP/IP (Tranmission Control Protocol/

Internet Protocol) which allowed users to implement a wide range of network

applications including network telephony, email, and network disk sharing. The

ARPANET was converted to a TCP/IP net in 1983 at which point it was split

into two nets: the MILNET for military applications and the ARPANET for

civilian applications. Throughout the 70's several other networks were devel 

oped. These included CSNET (connecting Computer Science Departments),

USENET (connecting UNIX computers), and BITNET (connecting academic

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