Computer viruses are malicious programs that can damage computers. They replicate by attaching themselves to other programs and spreading from computer to computer. Antivirus software identifies and removes viruses using a virus dictionary to examine files and detect known virus codes. It is important to regularly update antivirus software and scan computers to remove viruses and prevent further infection. Popular antivirus programs provide daily updates and scanning tools to detect and remove viruses through repair, quarantine, deletion or other actions.

1. Virus & Antivirus

2. What is a Computer Virus?
• A computer virus is a small program written to alter the way a
computer operates, without the permission or knowledge of the
user.
• It has an ability to replicate itself, thus continues to spread. We
can define compute virus also as a Malicious Software, a
program that can cause damage to a computer.
• The computer viruses can damage or corrupt data, modify
existing data, or degrade the performance of the system by
utilizing resources such as memory or disk space.
• It may spread through internet, carried by a removable medium
such as a Floppy disk, CD/DVD Drive, USB Drive and affect
other computers

3. How Viruses Work?
● Computer viruses are called viruses because they share some of the traits of
biological viruses. A computer virus passes from computer to computer like a
biological virus passes from person to person.
● Some of the major viruses are Melissa, Up Next, MyDoom, ILOVEYOU, Red
Code, Nimda, Leap – A.
● A virus is a small piece of software that piggybacks on real programs. For
example, a virus might attach itself to a program such as a spreadsheet
program. Each time the spreadsheet program runs, the virus runs, too, and it
has the chance to reproduce by attaching to other programs and wreak
havoc.
● experts estimate that the MyDoom virus infected approximately a quarter-
million computers in a single day in January 2004.

4. What is an Antivirus?
An antivirus software is a computer program that identifies
and removes computer viruses, and other malicious
software like Worms and Trojans from an infected
computer. Not only this, an antivirus software also protects
the computer from further virus attacks.
We should regularly run an antivirus program to scan
and remove any possible virus attacks from a computer.

5. How An Antivirus Works?
• The antivirus software examines each and every file in a
computer.
• It also examines its content with the virus definitions
stored in its virus dictionary.
• A virus dictionary is an inbuilt file belonging to an
antivirus software that contains code identified as a virus
by the antivirus authors.

6. Virus Updates
● An antivirus program should provide free virus updates
on a periodic basis.
● Most commercial antivirus software in today’s scenario
provide virus updates on daily basis.

7. How to use Antivirus software?
•Install antivirus software if you do not have it installed.
•Now, download the latest virus definitions updates from
the internet.
•Perform a full system scan.
•The scan result may show some virus detection.
•Click Repair, Quarantine, Rename, Delete or Ignore as
per your requirements.

8. Virus found!!
•Repair
•Quarantine
•Delete
•Rename
•Ignore

11. Popular Anti-Virus Softwares

12. By Naman Bhatnagar
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