INTROUCTION TO INTERNET
The internet is a network consisting of
thousands of small and large compute
networks. In other words internet can be
defined as a global network where
million of computers are connected to
All computers connected on the
net can exchange information by
following certain rules called Protocols.
Therefore a protocol is a set of rules
which the computers use to
communicate with one another across a
SERVICIES POVIDED BY INTERNET
1- World Wide Web (www)
2- E-Mail (Electronic mail)
3- News group
5- Bulleting Board Service
6- Video Conferencing
7- File Transfer Protocol (FTP)
10- Hyper Text Transfer Protocol (HTTP)
Components required to connect to
1- A Computer System
2- A Modem
3- An Internet Service Provider (ISP)
4- An Internet browsing software.
A modem is a computer device to connect
to and communicate with other computes
via a telephone line. Modem convents
digital signals to analog symbols, which is
known as Modulation and also converts the
analog signals to digital signals, known as
Demodulation. Hence the word Modem
comes from Modulator and Demodulator.
THERE ARE TWO TYPE OF MODEMS
AVAILABLE :1- Internal Modem
2- External Modem.
INTERNET SERVICE PROVIDER (ISP)
Internet Service Provides are companies
that provide the Internet connection against
charging some fee. ISPs use powerful
computes called Savers with high storage
capacity and memory, which is connected
with other savers through satellites all over
the world. The ISPs gives an account
number an password to its user to gain
access to the Internet.
When we want to use the internet,
you dial an get connected to an ISP. The
ISP then handles al the communication
between us and the Internet.
ISP IN INIDA
SOME OF THE ISPS IN INIDA ARE:-
• Manta On-Line
• Satyam On-Line
It is a software, which allows the user to
access and browse information on the
internet. Without a web browser internet
cannot be accessed. Internet Explorer,
Netscape Navigator, Opera an Mosaic are
common examples of web browses.
A website is a collection of web pages which
give information about an organization, a
topic etc. A website can contain many
Hypertext links which link to a piece of text
or graphic that is like to some other text,
graphic, page or file.
TYPES OF WEBSITES :1- .com for Commercial Purposes like
2- .org for Organizations like Congress.org
3- .edu for Educational Purposes like
4- .gov for Government like
UNIFORM RESOURCE LOCATOR (URL)
URL provides an address to locate any site
on the Internet. Every website has got a
distinct URL. With the help of the URL, the
web site is retrieved by the Web Browser.
The URL helps the user to identify and
locate any resource on the Internet.
Search Engine is a software that helps us to
locate Web Pages on the Internet that
contain information on the specified topics.
We can search for any topic, images, news,
video, meaning etc. using the search
SOME POPULAR SEARCH ENGINES
4- http// indiatimes.com
6- http// lycos.com etc.
A computer virus is a program intentionally
designed by a programmer for destroying
system files and data of other computers. A
virus program duplicates itself without any
instruction from the user and damages the
data on our disk by corrupting programs, or
even formatting the entire hard disk. In other
words we can say that virus simply
replicates. Virus corrupts or damages the
data without the knowledge of the user at a
very great speed.
How does virus infect a computer
Computer virus spread with the great speed
from one computer to another by means of
infected disks, networks, programs
downloaded from the Internet etc. a floppy
disk can also infect a computer. Some virus
programs are so well designed that they
have a pre-set date or time on which they
automatically. Virus can infect the display of
a file or keyboard or any program files as
word processor, database etc.
HOW DOES VIRUS SPREAD
Virus can easily spread from one system to
another by copying any infected application
on starting the computer system. This is
because the virus goes into the memory of
the computer and starts infecting each
application that gets executed by us. The
virus programs get transferred into a
computer through other virus infected
programs, which we copy from floppies,
CDs etc. examples of such viruses are
Michealangelo, Monkey etc.
Different types of virus:Boot virus
This type of virus infects the startup area of
the hard disk o floppy disk. They attach
themselves with the boot area and overwrite
on the original instructions and take up
control of the system. Booting means
stating the computer and loading the
EXAMPLES:Junkee, Ping Pong, Devil, Disk Killer etc.
This type of virus infect application
programs such as word processor,
database etc. When the infected fie is
executed, the virus gets activated and
remains present in the main memory
even when the execution of the file is
over. When you execute another fie,
the virus attaches itself to the new fie
and thus another file gets infected.
EXAMPLESEnigma, Trojan, Crazy, Yankee Doodle
These viruses attach themselves to the
operating system and infect the input/output
unit of the operating system. They always
stay in the memory, damage parts of the
operating system and then destroy
TROJAN HORSES AND WORMS
Trojan horses programs are those programs
that are useful to perform certain tasks. But
at the same time they damage files or data
in the system. This program destroys
Effects of virus
1- Viruses generally affect the software, files and folders of a
computer. Hardware components are generally immune to
2- Fie with .exe extensions are soft targets to viruses.
3- Viruses can infect boot records thereby causing booting
4- Other effects of viruses include corruption of data files,
periodic hang- ups, slow system performance, loss of data
5- Viruses can also alter the contents and the size of a file.
6- It can change the al the files names to a signal name.
7- It can erase programs or data.
8- It can overwrite entire directories.
9- It can create bad sectors in files and therefore destroy
parts of the files
1- Scan all floppies using antivirus software.
2- Write protect the floppies before coping
data from other computer system.
3- Keep backup of all data and files.
4- Prepare an emergency boot disk.
5- Update your Antivirus program
6- Restrict the use of your computer system
so that there is no unauthorized use.
We should not
1- Use floppies without scanning them
for possible viruses.
2- Run an unknown program without
using an antivirus to detect any viruses.
3- Allow everyone to use your computer
4- While using Internet do not download
anything from the Internet without
scanning for viruses.
Antivirus is a software designed to
detect and remove viruses from the
computer system. Some types of virus
are difficult to remove. Antivirus program
gets activated whenever the computer
system is booted up.
IT DETECTES THE VIRUS AND
REMOVES IT. ANTIVIRUS PROGRAM
ARE OF TWO TYPES:1- SCANNERS
Scanners are programs that scan the
disks to detect viruses. These programs
scan the disk for any known virus. After
scanning the disk and detecting the
virus, they inform the user about the
infected files. The user can then delete
the infected file or get it cleaned by an
Antidote are programmed to detect virus
and clean the infected disk. Cleaning
involves deleting the virus code from the
infected file e.g. an Antidote detects virus in
the boot area of a computer system. It will
then delete the virus code and rewrite the
programs back in their proper place.
SOME POPULAR ANTIVIRUS
SOFTWARES ARE:1- Norton Antivirus
3- Smart Dog
MADE BY – PRANJAL MISHRA
CLASS – 7TH A
ROLL NO. - 7037