This document provides information about computer viruses, how they spread, and their types. It explains that computer viruses are malicious programs that can replicate themselves and spread from one computer to another through email attachments, downloads, or infected files. Viruses can corrupt or delete files on a computer. The document outlines different types of viruses like overwrite viruses, boot viruses, and worms. It also lists some common symptoms of an infected computer like slow performance, missing files, error messages, and printing issues. It advises the reader to avoid opening unknown email attachments, get an antivirus program, and use online virus removal tools if infected.

1. WELCOME

2. Computer virus

3. What is a computer virus?
 Computer virus are small software programs that are
designed to spread from one computer to another and
to interface with computer operation.
 A virus might corrupt or delete data on your computer
,use your e-mail program to spread itself to other
computers ,or even erase everything on your hard disk
 Computer viruses are often spread by attachments in
e-mail messages or instant messaging messages. That
is why is essential that you never open e-mail
attachments unless you know who it’s from and you
are expecting it.
 Virus can be disguised as attachments of funny Images
, greeting cards , or audio and video files

4. • Computer viruses also spread through downloads on the
internet .
• To help avoid computer viruses , it’s essential that you keep
your computer current with the latest updates and
antivirus tools, stay informed about recent threats , run
your computer as a standard user and that you follow a few
basic rules when you surf the Internet, downloads files ,
and open attachments .
• Computer virus is a kind of malicious software written
intentionally to enter a computer without the user’s
permission or knowledge , with an ability to replicate it
self , thus continuing to spread . Some viruses do little but
replicate others can cause severe harm or adversely effect
program and performance of the system.

6. Types of virus
 There are different types of computer virus could be
classified . Let us have at look at them
 A virus should never be assumed harmless and left on
the system . Most common type of virus are mentioned
below.

7. Overwrite viruses
 Virus of this kind is characterized by fact that it
deletes the information contained in the files that it
infects , rendering them partially or totally useless
once they have been infected
 The only way to clean a file infected by an overwrite
virus is to delete the file completely ,thus losing the
original content
 Example : way trivial.88.d

8. Boot Viruses
 This type of viruses affects the boot sector of a floppy
or hard disk.
 This is a crucial part of a disk , in which information
on the disk itself is stored together with a program
that makes it possible to boot (start) the computer
from the disk.
 The best way of avoiding boot viruses is to ensure that
floppy disks are write-protected and never start your
computer with an unknown floppy disk in the disk
drive.
 Examples : AntiEXE , Polyboot.b.

9. Worms virus
 A worm is a program very similar to a virus ; it has the
ability to self-replicate , and can lead to negative
effects on your system and most importantly they are
detected and eliminating by antivirus.
 Examples: Mapson etc.,

11. A virus, once installed on your computer, can easily corrupt or delete data from
your computer. we have heard countless times from people, " But I did not open
any email attachments, how can I be infected?" While it is true that a majority of
viruses are hidden within email attachments, they can also be downloaded into our
computers in the form of images, videos, or even instant messages
Do not open email attachments if you do not know the sender, this is asking for
trouble. Lets move on to identifying infected computers., it is our responsibility to
quickly identify the signs of virus infections. Computers with virus infections will
often show some of the following symptoms. Please note, that the issues listed
below may be caused by several problems, such as spyware, and are not specific
to viruses. Your computer may be slow to start or shut down. You may be missing
data on your hard drive or, in worst case scenarios, lose all data on the drive. You
may experience strange error messages or you computer will shut down
unexpectedly. Your fonts may be distorted and overlap or you may experience
difficulties in printing.
If you do not have an anti virus program, first thing to do is get one! In the
meantime you may use the services of an online virus removal tool. Many of the
popular anti virus programs offer this service.

13. Thank you