InternetThe
Internet is a computer network made up of thousands of networks
worldwide. No one knows exactly how many computers are connected to the
Internet. It is certain, however, that these number in the millions.
No
one is in charge of the Internet. There are organizations which develop
technical aspects of this network and set standards for creating
applications on it, but no governing body is in control. The Internet
backbone, through which Internet traffic flows, is owned by private
companies.
All computers on the Internet communicate with one
another using the Transmission Control Protocol/Internet Protocol suite,
abbreviated to TCP/IP. Computers on the Internet use a client/server
architecture. This means that the remote server machine provides files
and services to the user's local client machine. Software can be
installed on a client computer to take advantage of the latest access
technology.
An
Internet user has access to a wide variety of services: electronic
mail, file transfer, vast information resources, interest group
membership, interactive collaboration, multimedia displays, real-time
broadcasting, shopping opportunities, breaking news, and much more.
The
Internet consists primarily of a variety of access protocols. Many of
these protocols feature programs that allow users to search for and
retrieve material made available by the protocol.
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COMPONENTS OF THE INTERNET
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WORLD WIDE WEBThe
World Wide Web (abbreviated as the Web or WWW) is a system of Internet
servers that supports hypertext to access several Internet protocols on a
single interface. Almost every protocol type available on the Internet
is accessible on the Web. This includes e-mail, FTP, Telnet, and Usenet
News. In addition to these, the World Wide Web has its own protocol:
HyperText Transfer Protocol, or HTTP. These protocols will be explained
later in this document.
The World Wide Web provides a single
interface for accessing all these protocols. This creates a convenient
and user-friendly environment. It is no longer necessary to be
conversant in these protocols within separate, command-level
environments. The Web gathers together these protocols into a single
system. Because of this feature, and because of the Web's ability to
work with multimedia and advanced programming languages, the Web is the
fastest-growing component of the Internet.
The
operation of the Web relies primarily on hypertext as its means of
information retrieval. HyperText is a document containing words that
connect to other documents. These words are called links and are
selectable by the user. A single hypertext document can contain links to
many documents. In the context of the Web, words or graphics may serve
as links to other documents, images, video, and sound. Links may or may
not follow a logical path, as each connection is programmed by the
creator of the source document. Overall, the Web contains a complex
virtual web of connections among a vast number of documents, graphics,
videos, and sounds.
Producing hypertext for the Web is
accomplished by creating documents with a language called HyperText
Markup Language, or HTML. With HTML, tags are placed within the text to
accomplish document formatting, visual features such as font size,
italics and bold, and the creation of hypertext links. Graphics and
multimedia may also be incorporated into an HTML document. HTML is an
evolving language, with new tags being added as each upgrade of the
language is developed and released. The World Wide Web Consortium (W3C),
led by Web founder Tim Berners-Lee, coordinates the efforts of
standardizing HTML. The W3C now calls the language XHTML and considers
it to be an application of the XML language standard.
The World
Wide Web consists of files, called pages or home pages, containing links
to documents and resources throughout the Internet.
The Web
provides a vast array of experiences including multimedia presentations,
real-time collaboration, interactive pages, radio and television
broadcasts, and the automatic "push" of information to a client
computer. Programming languages such as Java, JavaScript, Visual Basic,
Cold Fusion and XML are extending the capabilities of the Web. A growing
amount of information on the Web is served dynamically from content
stored in databases. The Web is therefore not a fixed entity, but one
that is in a constant state of development and flux.
E-MAILElectronic
mail, or e-mail, allows computer users locally and worldwide to
exchange messages. Each user of e-mail has a mailbox address to which
messages are sent. Messages sent through e-mail can arrive within a
matter of seconds.
A
powerful aspect of e-mail is the option to send electronic files to a
person's e-mail address. Non-ASCII files, known as binary files, may be
attached to e-mail messages. These files are referred to as MIME
attachments.MIME stands for Multimedia Internet Mail Extension, and was
developed to help e-mail software handle a variety of file types. For
example, a document created in Microsoft Word can be attached to an
e-mail message and retrieved by the recipient with the appropriate
e-mail program. Many e-mail programs, including Eudora, Netscape
Messenger, and Microsoft Outlook, offer the ability to read files
written in HTML, which is itself a MIME type.
TELNETTelnet
is a program that allows you to log into computers on the Internet and
use online databases, library catalogs, chat services, and more. There
are no graphics in Telnet sessions, just text. To Telnet to a computer,
you must know its address. This can consist of words (locis.loc.gov) or
numbers (140.147.254.3). Some services require you to connect to a
specific port on the remote computer. In this case, type the port number
after the Internet address. Example: telnet nri.reston.va.us 185.
Telnet
is available on the World Wide Web. Probably the most common Web-based
resources available through Telnet have been library catalogs, though
most catalogs have since migrated to the Web. A link to a Telnet
resource may look like any other link, but it will launch a Telnet
session to make the connection. A Telnet program must be installed on
your local computer and configured to your Web browser in order to work.
With
the increasing popularity of the Web, Telnet has become less frequently
used as a means of access to information on the Internet.
FTPFTP
stands for File Transfer Protocol. This is both a program and the
method used to transfer files between computers. Anonymous FTP is an
option that allows users to transfer files from thousands of host
computers on the Internet to their personal computer account. FTP sites
contain books, articles, software, games, images, sounds, multimedia,
course work, data sets, and more.
If
your computer is directly connected to the Internet via an Ethernet
cable, you can use one of several PC software programs, such as WS_FTP
for Windows, to conduct a file transfer.
FTP transfers can be
performed on the World Wide Web without the need for special software.
In this case, the Web browser will suffice. Whenever you download
software from a Web site to your local machine, you are using FTP. You
can also retrieve FTP files via search engines such as FtpFind, located
at /http://www.ftpfind.com/. This option is easiest because you do not
need to know FTP program commands.
E-MAIL DISCUSSION GROUPSOne
of the benefits of the Internet is the opportunity it offers to people
worldwide to communicate via e-mail. The Internet is home to a large
community of individuals who carry out active discussions organized
around topic-oriented forums distributed by e-mail. These are
administered by software programs. Probably the most common program is
the listserv.
A
great variety of topics are covered by listservs, many of them academic
in nature. When you subscribe to a listserv, messages from other
subscribers are automatically sent to your electronic mailbox. You
subscribe to a listserv by sending an e-mail message to a computer
program called a listserver. Listservers are located on computer
networks throughout the world. This program handles subscription
information and distributes messages to and from subscribers. You must
have a e-mail account to participate in a listserv discussion group.
Visit Tile.net at /http://tile.net/ to see an example of a site that
offers a searchablecollection of e-mail discussion groups.
Majordomo
and Listproc are two other programs that administer e-mail discussion
groups. The commands for subscribing to and managing your list
memberships are similar to those of listserv.
USENET NEWSUsenet
News is a global electronic bulletin board system in which millions of
computer users exchange information on a vast range of topics. The major
difference between Usenet News and e-mail discussion groups is the fact
that Usenet messages are stored on central computers, and users must
connect to these computers to read or download the messages posted to
these groups. This is distinct from e-mail distribution, in which
messages arrive in the electronic mailboxes of each list member.
Usenet
itself is a set of machines that exchanges messages, or articles, from
Usenet discussion forums, called newsgroups. Usenet administrators
control their own sites, and decide which (if any) newsgroups to sponsor
and which remote newsgroups to allow into the system.
There are
thousands of Usenet newsgroups in existence. While many are academic in
nature, numerous newsgroups are organized around recreational topics.
Much serious computer-related work takes place in Usenet discussions. A
small number of e-mail discussion groups also exist as Usenet
newsgroups.
The Usenet newsfeed can be read by a variety of
newsreader software programs. For example, the Netscape suite comes with
a newsreader program called Messenger. Newsreaders are also available
as standalone products.
FAQ, RFC, FYIFAQ
stands for Frequently Asked Questions. These are periodic postings to
Usenet newsgroups that contain a wealth of information related to the
topic of the newsgroup. Many FAQs are quite extensive. FAQs are
available by subscribing to individual Usenet newsgroups. A Web-based
collection of FAQ resources has been collected by The Internet FAQ
Consortium and is available at /http://www.faqs.org/.
RFC
stands for Request for Comments. These are documents created by and
distributed to the Internet community to help define the nuts and bolts
of the Internet. They contain both technical specifications and general
information.
FYI stands for For Your Information. These notes are a subset of RFCs and contain information of interest to new Internet users.
CHAT & INSTANT MESSENGINGChat
programs allow users on the Internet to communicate with each other by
typing in real time. They are sometimes included as a feature of a Web
site, where users can log into the "chat room" to exchange comments and
information about the topics addressed on the site. Chat may take other,
more wide-ranging forms. For example, America Online is well known for
sponsoring a number of topical chat rooms.
Internet
Relay Chat (IRC) is a service through which participants can
communicate to each other on hundreds of channels. These channels are
usually based on specific topics. While many topics are frivolous,
substantive conversations are also taking place. To access IRC, you must
use an IRC software program.
A variation of chat is the
phenomenon of instant messenging. With instant messenging, a user on the
Web can contact another user currently logged in and type a
conversation. Most famous is America Online's Instant Messenger. ICQ,
MSN and Yahoo are other commonly-used chat programs.
Other types of real-time communication are addressed in the tutorial Understanding the World Wide Web.
MUD/MUSH/MOO/MUCK/DUM/MUSE
MUD
stands for Multi User Dimension. MUDs, and their variations listed
above, are multi-user virtual reality games based on simulated worlds.
Traditionally text based, graphical MUDs now exist. There are MUDs of
all kinds on the Internet, and many can be joined free of charge.
in the Security Status bar. The Security Status bar is located on the
right side of the Address bar. You can click the lock to view the
identity of the website.
