Internet
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, theintranet 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.
The most widely used
part of the Internet is the World Wide Web (often abbreviated "WWW" or called "the
Web"). Its outstanding feature is hypertext, a method of instant cross-referencing. In
most Web sites, certain words or phrases appear in text of a different color
than the rest; often this text is also underlined. When you select one of these
words or phrases, you will be transferred to the site or page that is relevant
to this word or phrase. Sometimes there are buttons, images, or portions of
images that are "clickable." If you move the pointer over a spot on a
Web site and the pointer changes into a hand, this indicates that you can click
and be transferred to another site.
Using the Web, you have
access to millions of pages of information. Web browsing is done with a
Web browser, the most popular of
which are Microsoft Internet Explorer and Netscape Navigator. The appearance of
a particular Web site may vary slightly depending on the browser you use. Also,
later versions of a particular browser are able to render more "bells and
whistles" such as animation, virtual reality, sound, and music files, than
earlier versions.
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