The Internet, sometimes called simply
"the Net," is a worldwide system of computer networks - a network of
networks
in which users at any one computer can, if they have
permission, get information from any other computer (and sometimes talk
directly to users at other computers). It was conceived by the Advanced
Research Projects Agency
(ARPA) of the U.S. government in 1969 and was first known as the ARPANET.
The original aim was to create a network that would allow users of a
research computer at one university to be able to "talk to" research
computers at other universities. A side benefit of ARPANet''s design was
that, because messages could be routed or rerouted in more than one
direction, the network could continue to function even if parts of it
were destroyed in the event of a military attack or other disaster.
Today, the Internet is a public, cooperative, and self-sustaining
facility accessible to hundreds of millions of people worldwide.
Physically, the Internet uses a portion of the total resources of the currently existing public telecommunication networks.
Technically, what distinguishes the Internet is its use of a set of protocols called TCP/IP (for Transmission
Control Protocol/Internet Protocol). Two recent adaptations of Internet technology,
the intranet and the extranet,
also make use of the TCP/IP protocol.
For many Internet users, electronic mail (e-mail)
has practically replaced the Postal Service for short written
transactions. Electronic mail is the most widely used application
on the Net. You can also carry on live
"
conversations" with other computer users, using Internet Relay Chat (IRC). More recently, Internet telephony
hardware and software allows real-time voice
conversations.