Computer viruses are programs that replicate and spread like biological viruses. They can slow down systems, erase files, or crash computers by formatting disks. Viruses spread by attaching to other files and transferring via external drives or infected repair disks. There are several types of viruses like boot, polymorphic, macro, and worm viruses as well as Trojan horses. To prevent viruses, users should install antivirus software, regularly update it, be wary of email attachments, avoid unnecessary downloads, and only install registered software. Popular antivirus programs include Norton, McAfee, Avast, Quick Heal, and Panda.

2.  Computer viruses are a type of software
program that, like biological virus
reproduces and spread itself
 Some Virus may display on a message on
the screen ,others may slow down the pc
 They can also erase files or even format
your floppy or hard disk and the crash the
system

3.  Letters looks like they are falling to the bottom of
the screen.
 The computer system becomes slow.
 The size of available free memory reduces.
 The hard disk runs out of space.
 The computer does not boot.

5.  Computer viruses spread by attaching
themselves to other computer program files
 When you exchange a file or pen drive with a
virus, the virus spreads from one computer to the
another
 Viruses also spreads when a Computer Engineer
comes to repair your system and puts his/her
diagnostics disks in your PC

6.  Boot viruses:- The boot virus copies the virus code in the
boot sector
 Polymorphic viruses:- They are coded in such a way that
they infect a system and change their signature
 Macro viruses:- Macros are blocks of code written to
automate frequently performed tasks and embedded in a
program file
 Worms:- Worms are program that replicate and spread to
other system
 Trojans:- A Trojan is a program file that claims to do
something but it actually does something that is not required

7.  Install an Antivirus software
 Regularly update the program
 Open email attachment files only if you are expecting the
attached files, or the sender is known and has confirmed
sending the file
 Try to avoid downloading and installing software from the
Internet
 Install only registered copies of software on the system

8.  Norton Anti-Virus
 MacAfee
 Avast
 Quick Heal
 Panda

9.  For better and safe computation anti-virus
software should be installed and be
helpful for global network system freely.