The document provides an overview of the Internet and how it functions. It can be summarized as follows:
The Internet is a global network of networks that connects millions of computers around the world. It was originally developed by researchers but is now used widely for various purposes like email, web publishing, messaging, banking and more. Key protocols like TCP/IP allow for the transmission of data between different networks and systems. Users can access the Internet through direct connections, dial-up, or broadband. Popular applications include email, instant messaging, file transfers, remote access and more. The client-server model supports distributed applications across the network.
2. 8.1 THE INTERNET: A NETWORK
OF NETWORKS
The Internet is an interconnected network of thousands of
networks linking academic, research, government, and
commercial institutions, other organizations, and
individuals. The Internet is a technology, a tool, and a
culture. It was originally designed by computer scientists
for computer scientists, but today its used by people in all
walks of life all over the world.
The Internet provides scientists, engineers, researchers,
educators, students, business people, consumers, and
others with a variety of services, including:
Electronic mail (e-mail)
Web publishing
Instant messaging
Network newsgroups
Banking
Research
3. 8.1.2 INTERNET PROTOCOLS
The protocols at the heart of the Internet are
called TCP/IP (Transmission Control
Protocol/Internet Protocol). They were developed
as an experiment in internetworkingconnecting
different types of networks and computer
systems. The TCP/IP specifications were
published as open standards, not owned by any
company. They define how information can be
transferred between machines and how machines
on the network can be identified with unique
addresses.
4. 8.1.3 INTERNET ACCESS OPTIONS
There are three common ways users can connect their
computers to the Internet to take advantage of some
or all Internet services:
Direct (dedicated) connection, which provides
the fastest, most reliable service.
Dial-up connections use a modem and standard
phone line. A full-access dial-up connection
offers most of the advantages of direct
connection, but is limited by modem speed.
Broadband connections include DSL, cable
modem connections, and satellite connections.
5. INTERNET SERVICE PROVIDERS
(ISPS)
Offer several connection options at different
prices. In some cities inexpensive or free access
to the Internet is available through a free net
a local bulletin board system designed to provide
community access to on-line forums,
announcements, and services. Many computer
networks, bulletin board systems, and on-line
services provide varying degrees of Internet
access through gateways. A gateway is a
computer connected to two networksin this
case, the Internet and an outside networkthat
translates communication protocols and transfers
information between the two.
6. 8.1.4 INTRANETS AND EXTRANETS
For many organizations, Internet protocols and
software are more important than the Net itself.
Members of these organizations communicate
through intranetsself-contained
intraorganizational networks that are
designed using the same technology as the
Internet. Some private TCP/IP networks are
designed for outside use by customers,
clients, and business partners of the
organization. These networks, often called
extranets, are typically for electronic
commercebusiness transactions through
electronic networks.
7. 8.2 INTERNET APPLICATIONS:
COMMUNICATION AND CONNECTION
Working with Internet applications is different
from working with word processors or
spreadsheets because of the distributed nature of
the Internet and the client/server model used
by most Internet applications. In the
client/server model, a client program asks
for information and a server program fields
the request and provides the requested
information from databases and documents.
Two different users might access the same
server using completely different client
applications with different user interfaces.
8. 8.2.1 INTERNET ADDRESSES
The most popular reason for connecting to the
Internet is electronic mail. You can send messages to
anyone with an Internet link, provided you know his
or her Internet address.
A persons e-mail address is made up of two parts
separated by an at sign (@)the persons user name
(login name), and the host namethe name of the
host computer or network where the user receives
mail. Heres the basic form: study@Regent.ac.za.
The host is named using whats called the domain
name system (DNS)a system that translates the
computers numerical IP address into something
thats easier for humans to read and remember. The
DNS uses a string of names separated by dots to
specify the exact Internet location of the host
computer. The words in the domain name are
arranged hierarchically from little to big.
9. 8.2.2 E-MAIL ON THE INTERNET
Basic e-mail can be handled by a character-based
program like PINE or (if you have a full Internet
connection) a graphical client program like
Netscape, Microsoft Outlook Express, or Eudora.
Standard Internet mail messages are plain
ASCII text. Formatted word processor
documents, pictures, and other multimedia files
usually need to be temporarily converted to
ASCII using some kind of encoding scheme before
they can be sent through Internet mail; these
encoded documents are sent as attachments to
text messages.
10. 8.2.4 NETWORK NEWS
You can participate in special-interest
discussions and debates without overloading your
mailbox by taking advantage of the hundreds of
Usenet newsgroups. These are public
discussions that you can check into and out
of whenever you want; all messages are
posted on virtual bulletin boards for anyone
to read. Newsgroups are organized
hierarchically, with dot names like
rec.music.makers.percussion and
soc.culture.french. To explore network
newsgroups, you need a client program that
can serve as a news reader.
11. 8.2.5 REAL-TIME
COMMUNICATION
Mailing lists and news groups are delayed, or
asynchronous communication, because the
sender and the recipient dont have to be logged
in at the same time. The Internet offers
programs for real-time communication, too.
Text-based options include Talk and Internet
Relay Chat (IRC). Newer, easier to use instant
message systems such as AOLs allow users to
create buddy lists and chat with buddies
who are logged in. Many new programs allow
you to use a computers microphone and
speaker to turn the Internet into a toll-free long
distance telephone service. Some even allow
two-way video teleconferences.
12. 8.2.6 TELNET AND FTP
To find and retrieve information located on
remote Internet sites, Net explorers have
traditionally used two software tools:
remote login and file transfer. Remote login
allows users to connect to hosts all over the
world from just about anywhere. The
protocol that makes remote login possible is
called telnet, which is also the name of the
UNIX command thats used for remote login
and the name of a program that executes
the Telnet command from directly
connected Macintosh and Windows PCs.
13. FILE TRANSFER PROTOCOL
The Internets file transfer protocol,
commonly called just FTP, can transfer files
from remote sites to users host computers.
Many sites allow anonymous FTP so you
can collect files without officially logging
in. Most files in net archives are
compressedmade smaller using special
encoding schemes. Compression saves
storage space on disks and saves
transmission time when files are
transferred through networks.