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Internet, a
collection of computer networks that operate to
common standards and enable the computers and
the programs they run to communicate directly.
There are many small-scale, controlled-access
“enterprise internets”, but the term is usually
applied to the global, publicly accessible
network, called simply the Internet or Net. By
the end of 2002, more than 100,000 networks and
around 120 million users were connected via the
Internet.
Internet connection is usually accomplished
using international standards collectively
called TCP/IP (Transmission Control
Protocol/Internet Protocol), which are issued by
an organization called the Internet Engineering
Task Force, combined with a network registration
process, and with the aid of public providers of
Internet access services, known as Internet
Service Providers or ISPs.
Each connected computer—called an Internet
host—is provided with a unique Internet Protocol
(IP) address—198.105.232.1, for example. For
obvious reasons, the IP address has become known
as the “dot address” of a computer. Although
very simple and effective for network operation,
dot addresses are not very user-friendly. Hence
the introduction of the Domain Name System (DNS)
that allows for the assignment of meaningful or
memorable names to numbers. DNS allows Internet
hosts to be organized around domain names: for
example, “microsoft.com” is a domain assigned to
the Microsoft Corporation, with the suffix “com”
signifying a commercial organization.
“ftp.microsoft.com” is an Internet host within
that domain. Each part of the domain still has
an IP or dot address, which is used by the
network elements to deliver information. From a
user point of view, though, the IP address is
translated (or “resolved”) by DNS into the now
familiar format.
The suffix .com is called a generic top-level
domain name, and before 2001 there were just
three of these (.com, .net, and .org), with .edu
and .gov restricted to educational institutions
and government agencies respectively. As a
result of the rapid growth in Internet use,
seven new top-level domain names have been
prepared for use, some by specific sectors
(.aero, .coop, and .museum) and some for general
use (.biz, .info, .pro, and .name).
Internets are constructed using virtually any
kind of electronic transmission medium, such as
optical-fiber or copper-wire telephone lines, or
radio or microwave channels. They can also
connect almost any kind of computer or operating
system; and they are operated in such a way as
to be “self-aware” of their capabilities.
The great scale and universality of the public
Internet results in its use to connect many
other kinds of computer networks and
services—including online information and
shopping services—via systems called gateways.
As a result of all these features, internets are
an ideal means of building a very robust
universal information infrastructure throughout
the world. The rapid growth of online shops,
information services, and electronic business
applications is testament to the inherent
flexibility of the Net.
SERVICES
Internets support thousands of different kinds
of operational and experimental services. A few
of the most popular include the following:
E-mail (electronic mail) allows a message
to be sent from one person to another, or to
many others, via computer. Internet has its own
e-mail standards that have also become the means
of interconnecting most of the world's e-mail
systems. Internet e-mail addresses usually have
a form such as “editor@encarta.microsoft.com”,
where “editor” is the e-mail account name, and
“encarta.microsoft.com” is the domain identity
of the computer hosting the account. E-mail can
also be used to create collaborative groups
through the use of special e-mail accounts
called “reflectors” or “exploders” that
automatically redistribute mail sent to the
address.
The
World Wide Web (WWW) allows the seamless
creation and use of elegant point-and-click
hypermedia presentations, linked across the
Internet in a way that creates a vast open
knowledge repository, through which users can
easily browse.
Gopher is a system that allows the
creation and use of directories of files held on
computers on the Internet, and builds links
across the Internet in a manner that allows
users to browse through the files.
FTP (File Transfer Protocol) is a set of
conventions allowing easy transfer of files
between host computers. This remains the biggest
use of the Internet, especially for software
distribution, and many public distribution sites
now exist.
Usenet allows automatic global
distribution of news messages among thousands of
user groups, called newsgroups.
Telnet is the system that allows a user
to “log in” to a remote computer, and make use
of it.
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